Add cross-compilation results for GNU/Hurd.

* m4/calloc.m4: Add GNU/Hurd guess.
* m4/cbrtl.m4: Likewise.
* m4/ceil.m4: Likewise.
* m4/ceilf.m4: Likewise.
* m4/ceill.m4: Likewise.
* m4/chown.m4: Likewise.
* m4/duplocale.m4: Likewise.
* m4/exp2l.m4: Likewise.
* m4/expm1.m4: Likewise.
* m4/fchdir.m4: Likewise.
* m4/floor.m4: Likewise.
* m4/floorf.m4: Likewise.
* m4/fmod.m4: Likewise.
* m4/fmodf.m4: Likewise.
* m4/fmodl.m4: Likewise.
* m4/getcwd.m4: Likewise.
* m4/getgroups.m4: Likewise.
* m4/gettimeofday.m4: Likewise.
* m4/hypot.m4: Likewise.
* m4/hypotf.m4: Likewise.
* m4/hypotl.m4: Likewise.
* m4/link-follow.m4: Likewise.
* m4/link.m4: Likewise.
* m4/linkat.m4: Likewise.
* m4/log.m4: Likewise.
* m4/log10.m4: Likewise.
* m4/log10f.m4: Likewise.
* m4/log1p.m4: Likewise.
* m4/log1pf.m4: Likewise.
* m4/log1pl.m4: Likewise.
* m4/log2.m4: Likewise.
* m4/log2f.m4: Likewise.
* m4/logf.m4: Likewise.
* m4/lstat.m4: Likewise.
* m4/malloc.m4: Likewise.
* m4/mbrlen.m4: Likewise.
* m4/mbrtowc.m4: Likewise.
* m4/mkdir.m4: Likewise.
* m4/mkfifo.m4: Likewise.
* m4/mknod.m4: Likewise.
* m4/mkstemp.m4: Likewise.
* m4/modf.m4: Likewise.
* m4/modff.m4: Likewise.
* m4/modfl.m4: Likewise.
* m4/printf.m4: Likewise.
* m4/pselect.m4: Likewise.
* m4/ptsname.m4: Likewise.
* m4/putenv.m4: Likewise.
* m4/readlink.m4: Likewise.
* m4/realloc.m4: Likewise.
* m4/remainder.m4: Likewise.
* m4/remainderf.m4: Likewise.
* m4/remainderl.m4: Likewise.
* m4/rmdir.m4: Likewise.
* m4/round.m4: Likewise.
* m4/roundf.m4: Likewise.
* m4/roundl.m4: Likewise.
* m4/select.m4: Likewise.
* m4/setenv.m4: Likewise.
* m4/signbit.m4: Likewise.
* m4/sleep.m4: Likewise.
* m4/stat.m4: Likewise.
* m4/strerror.m4: Likewise.
* m4/strtok_r.m4: Likewise.
* m4/symlink.m4: Likewise.
* m4/symlinkat.m4: Likewise.
* m4/trunc.m4: Likewise.
* m4/truncf.m4: Likewise.
* m4/truncl.m4: Likewise.
* m4/tzset.m4: Likewise.
* m4/ungetc.m4: Likewise.
* m4/usleep.m4: Likewise.
* m4/wcwidth.m4: Likewise.

73 files changed, 535 insertions, 538 deletions

diff --git a/m4/calloc.m4 b/m4/calloc.m4
index 04a1a62692..2d5b1107a4 100644
--- a/m4/calloc.m4
+++ b/m4/calloc.m4
@@ -1,4 +1,4 @@
-# calloc.m4 serial 17
+# calloc.m4 serial 18
 
 # Copyright (C) 2004-2017 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -38,12 +38,12 @@ AC_DEFUN([_AC_FUNC_CALLOC_IF],
        [ac_cv_func_calloc_0_nonnull=yes],
        [ac_cv_func_calloc_0_nonnull=no],
        [case "$host_os" in
-                  # Guess yes on glibc systems.
-          *-gnu*) ac_cv_func_calloc_0_nonnull="guessing yes" ;;
-                  # Guess yes on native Windows.
-          mingw*) ac_cv_func_calloc_0_nonnull="guessing yes" ;;
-                  # If we don't know, assume the worst.
-          *)      ac_cv_func_calloc_0_nonnull="guessing no" ;;
+                         # Guess yes on glibc systems.
+          *-gnu* | gnu*) ac_cv_func_calloc_0_nonnull="guessing yes" ;;
+                         # Guess yes on native Windows.
+          mingw*)        ac_cv_func_calloc_0_nonnull="guessing yes" ;;
+                         # If we don't know, assume the worst.
+          *)             ac_cv_func_calloc_0_nonnull="guessing no" ;;
         esac
        ])])
   case "$ac_cv_func_calloc_0_nonnull" in
diff --git a/m4/cbrtl.m4 b/m4/cbrtl.m4
index 3fe797982c..86af9d92a0 100644
--- a/m4/cbrtl.m4
+++ b/m4/cbrtl.m4
@@ -1,4 +1,4 @@
-# cbrtl.m4 serial 6
+# cbrtl.m4 serial 7
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -72,12 +72,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_cbrtl_ieee=yes],
               [gl_cv_func_cbrtl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_cbrtl_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_cbrtl_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_cbrtl_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_cbrtl_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_cbrtl_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_cbrtl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/ceil.m4 b/m4/ceil.m4
index 72443a739c..118a731b2e 100644
--- a/m4/ceil.m4
+++ b/m4/ceil.m4
@@ -1,4 +1,4 @@
-# ceil.m4 serial 10
+# ceil.m4 serial 11
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -46,12 +46,12 @@ int main (int argc, char *argv[])
             [gl_cv_func_ceil_ieee=yes],
             [gl_cv_func_ceil_ieee=no],
             [case "$host_os" in
-                       # Guess yes on glibc systems.
-               *-gnu*) gl_cv_func_ceil_ieee="guessing yes" ;;
-                       # Guess yes on native Windows.
-               mingw*) gl_cv_func_ceil_ieee="guessing yes" ;;
-                       # If we don't know, assume the worst.
-               *)      gl_cv_func_ceil_ieee="guessing no" ;;
+                              # Guess yes on glibc systems.
+               *-gnu* | gnu*) gl_cv_func_ceil_ieee="guessing yes" ;;
+                              # Guess yes on native Windows.
+               mingw*)        gl_cv_func_ceil_ieee="guessing yes" ;;
+                              # If we don't know, assume the worst.
+               *)             gl_cv_func_ceil_ieee="guessing no" ;;
              esac
             ])
           LIBS="$save_LIBS"
diff --git a/m4/ceilf.m4 b/m4/ceilf.m4
index 7c83e05ab9..bf044cb45c 100644
--- a/m4/ceilf.m4
+++ b/m4/ceilf.m4
@@ -1,4 +1,4 @@
-# ceilf.m4 serial 15
+# ceilf.m4 serial 16
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -53,12 +53,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_ceilf_ieee=yes],
               [gl_cv_func_ceilf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_ceilf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_ceilf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_ceilf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_ceilf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_ceilf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_ceilf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/ceill.m4 b/m4/ceill.m4
index 54bf8dd35d..ed098a960e 100644
--- a/m4/ceill.m4
+++ b/m4/ceill.m4
@@ -1,4 +1,4 @@
-# ceill.m4 serial 16
+# ceill.m4 serial 17
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -52,12 +52,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_ceill_ieee=yes],
               [gl_cv_func_ceill_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_ceill_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_ceill_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_ceill_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_ceill_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_ceill_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_ceill_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/chown.m4 b/m4/chown.m4
index cf2f35f742..0d5199302b 100644
--- a/m4/chown.m4
+++ b/m4/chown.m4
@@ -1,4 +1,4 @@
-# serial 28
+# serial 29
 # Determine whether we need the chown wrapper.
 
 dnl Copyright (C) 1997-2001, 2003-2005, 2007, 2009-2017 Free Software
@@ -46,12 +46,12 @@ AC_DEFUN([AC_FUNC_CHOWN],
        [ac_cv_func_chown_works=yes],
        [ac_cv_func_chown_works=no],
        [case "$host_os" in # ((
-                  # Guess yes on glibc systems.
-          *-gnu*) ac_cv_func_chown_works="guessing yes" ;;
-                  # Guess no on native Windows.
-          mingw*) ac_cv_func_chown_works="guessing no" ;;
-                  # If we don't know, assume the worst.
-          *)      ac_cv_func_chown_works="guessing no" ;;
+                         # Guess yes on glibc systems.
+          *-gnu* | gnu*) ac_cv_func_chown_works="guessing yes" ;;
+                         # Guess no on native Windows.
+          mingw*)        ac_cv_func_chown_works="guessing no" ;;
+                         # If we don't know, assume the worst.
+          *)             ac_cv_func_chown_works="guessing no" ;;
         esac
        ])
      rm -f conftest.chown
diff --git a/m4/duplocale.m4 b/m4/duplocale.m4
index a5eb6cf5bb..40948f98d5 100644
--- a/m4/duplocale.m4
+++ b/m4/duplocale.m4
@@ -1,4 +1,4 @@
-# duplocale.m4 serial 9
+# duplocale.m4 serial 10
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -77,7 +77,7 @@ int main ()
          [dnl Guess it works except on glibc < 2.12, uClibc, AIX, and NetBSD.
           case "$host_os" in
             aix* | netbsd*) gl_cv_func_duplocale_works="guessing no";;
-            *-gnu*)
+            *-gnu* | gnu*)
               AC_EGREP_CPP([Unlucky], [
 #include <features.h>
 #ifdef __GNU_LIBRARY__
diff --git a/m4/exp2l.m4 b/m4/exp2l.m4
index 93edca305a..acc3bc3a2e 100644
--- a/m4/exp2l.m4
+++ b/m4/exp2l.m4
@@ -1,4 +1,4 @@
-# exp2l.m4 serial 4
+# exp2l.m4 serial 5
 dnl Copyright (C) 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -64,12 +64,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_exp2l_ieee=yes],
               [gl_cv_func_exp2l_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_exp2l_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_exp2l_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_exp2l_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_exp2l_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_exp2l_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_exp2l_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/expm1.m4 b/m4/expm1.m4
index fa62f8727c..1a62975204 100644
--- a/m4/expm1.m4
+++ b/m4/expm1.m4
@@ -1,4 +1,4 @@
-# expm1.m4 serial 4
+# expm1.m4 serial 5
 dnl Copyright (C) 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -85,12 +85,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_expm1_ieee=yes],
               [gl_cv_func_expm1_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_expm1_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_expm1_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_expm1_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_expm1_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_expm1_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_expm1_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/fchdir.m4 b/m4/fchdir.m4
index 0ef04ed8e9..af67f9c63c 100644
--- a/m4/fchdir.m4
+++ b/m4/fchdir.m4
@@ -1,4 +1,4 @@
-# fchdir.m4 serial 22
+# fchdir.m4 serial 23
 dnl Copyright (C) 2006-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -31,12 +31,12 @@ AC_DEFUN([gl_FUNC_FCHDIR],
         [gl_cv_func_open_directory_works=yes],
         [gl_cv_func_open_directory_works=no],
         [case "$host_os" in
-                   # Guess yes on glibc systems.
-           *-gnu*) gl_cv_func_open_directory_works="guessing yes" ;;
-                   # Guess no on native Windows.
-           mingw*) gl_cv_func_open_directory_works="guessing no" ;;
-                   # If we don't know, assume the worst.
-           *)      gl_cv_func_open_directory_works="guessing no" ;;
+                          # Guess yes on glibc systems.
+           *-gnu* | gnu*) gl_cv_func_open_directory_works="guessing yes" ;;
+                          # Guess no on native Windows.
+           mingw*)        gl_cv_func_open_directory_works="guessing no" ;;
+                          # If we don't know, assume the worst.
+           *)             gl_cv_func_open_directory_works="guessing no" ;;
          esac
         ])])
     case "$gl_cv_func_open_directory_works" in
diff --git a/m4/floor.m4 b/m4/floor.m4
index 0f99200407..88b4eb500d 100644
--- a/m4/floor.m4
+++ b/m4/floor.m4
@@ -1,4 +1,4 @@
-# floor.m4 serial 9
+# floor.m4 serial 10
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -42,12 +42,12 @@ int main (int argc, char *argv[])
             [gl_cv_func_floor_ieee=yes],
             [gl_cv_func_floor_ieee=no],
             [case "$host_os" in
-                       # Guess yes on glibc systems.
-               *-gnu*) gl_cv_func_floor_ieee="guessing yes" ;;
-                       # Guess yes on native Windows.
-               mingw*) gl_cv_func_floor_ieee="guessing yes" ;;
-                       # If we don't know, assume the worst.
-               *)      gl_cv_func_floor_ieee="guessing no" ;;
+                              # Guess yes on glibc systems.
+               *-gnu* | gnu*) gl_cv_func_floor_ieee="guessing yes" ;;
+                              # Guess yes on native Windows.
+               mingw*)        gl_cv_func_floor_ieee="guessing yes" ;;
+                              # If we don't know, assume the worst.
+               *)             gl_cv_func_floor_ieee="guessing no" ;;
              esac
             ])
           LIBS="$save_LIBS"
diff --git a/m4/floorf.m4 b/m4/floorf.m4
index 2f7e604fa0..45c83c1a14 100644
--- a/m4/floorf.m4
+++ b/m4/floorf.m4
@@ -1,4 +1,4 @@
-# floorf.m4 serial 14
+# floorf.m4 serial 15
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -49,12 +49,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_floorf_ieee=yes],
               [gl_cv_func_floorf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_floorf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_floorf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_floorf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_floorf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_floorf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_floorf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/fmod.m4 b/m4/fmod.m4
index efc1dc968e..69c81c8df2 100644
--- a/m4/fmod.m4
+++ b/m4/fmod.m4
@@ -1,4 +1,4 @@
-# fmod.m4 serial 5
+# fmod.m4 serial 6
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -58,12 +58,12 @@ int main (int argc, char *argv[])
             [gl_cv_func_fmod_ieee=yes],
             [gl_cv_func_fmod_ieee=no],
             [case "$host_os" in
-                       # Guess yes on glibc systems.
-               *-gnu*) gl_cv_func_fmod_ieee="guessing yes" ;;
-                       # Guess yes on native Windows.
-               mingw*) gl_cv_func_fmod_ieee="guessing yes" ;;
-                       # If we don't know, assume the worst.
-               *)      gl_cv_func_fmod_ieee="guessing no" ;;
+                              # Guess yes on glibc systems.
+               *-gnu* | gnu*) gl_cv_func_fmod_ieee="guessing yes" ;;
+                              # Guess yes on native Windows.
+               mingw*)        gl_cv_func_fmod_ieee="guessing yes" ;;
+                              # If we don't know, assume the worst.
+               *)             gl_cv_func_fmod_ieee="guessing no" ;;
              esac
             ])
           LIBS="$save_LIBS"
diff --git a/m4/fmodf.m4 b/m4/fmodf.m4
index fb5c88eabb..6bdfffa769 100644
--- a/m4/fmodf.m4
+++ b/m4/fmodf.m4
@@ -1,4 +1,4 @@
-# fmodf.m4 serial 7
+# fmodf.m4 serial 8
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -59,12 +59,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_fmodf_ieee=yes],
               [gl_cv_func_fmodf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_fmodf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_fmodf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_fmodf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_fmodf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_fmodf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_fmodf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/fmodl.m4 b/m4/fmodl.m4
index 110ba8fed0..3a7c4825d0 100644
--- a/m4/fmodl.m4
+++ b/m4/fmodl.m4
@@ -1,4 +1,4 @@
-# fmodl.m4 serial 7
+# fmodl.m4 serial 8
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -70,12 +70,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_fmodl_ieee=yes],
               [gl_cv_func_fmodl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_fmodl_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_fmodl_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_fmodl_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_fmodl_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_fmodl_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_fmodl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/getcwd.m4 b/m4/getcwd.m4
index a3f62c4622..33def5c803 100644
--- a/m4/getcwd.m4
+++ b/m4/getcwd.m4
@@ -6,7 +6,7 @@
 # with or without modifications, as long as this notice is preserved.
 
 # Written by Paul Eggert.
-# serial 14
+# serial 15
 
 AC_DEFUN([gl_FUNC_GETCWD_NULL],
   [
@@ -48,12 +48,12 @@ AC_DEFUN([gl_FUNC_GETCWD_NULL],
         [gl_cv_func_getcwd_null=yes],
         [gl_cv_func_getcwd_null=no],
         [[case "$host_os" in
-                     # Guess yes on glibc systems.
-            *-gnu*)  gl_cv_func_getcwd_null="guessing yes";;
-                     # Guess yes on Cygwin.
-            cygwin*) gl_cv_func_getcwd_null="guessing yes";;
-                     # If we don't know, assume the worst.
-            *)       gl_cv_func_getcwd_null="guessing no";;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_getcwd_null="guessing yes";;
+                           # Guess yes on Cygwin.
+            cygwin*)       gl_cv_func_getcwd_null="guessing yes";;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_getcwd_null="guessing no";;
           esac
         ]])])
 ])
diff --git a/m4/getgroups.m4 b/m4/getgroups.m4
index 17f7409944..8a52e17fe4 100644
--- a/m4/getgroups.m4
+++ b/m4/getgroups.m4
@@ -1,4 +1,4 @@
-# serial 19
+# serial 20
 
 dnl From Jim Meyering.
 dnl A wrapper around AC_FUNC_GETGROUPS.
@@ -40,10 +40,10 @@ AC_DEFUN([AC_FUNC_GETGROUPS],
          [ac_cv_func_getgroups_works=yes],
          [ac_cv_func_getgroups_works=no],
          [case "$host_os" in # ((
-                    # Guess yes on glibc systems.
-            *-gnu*) ac_cv_func_getgroups_works="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      ac_cv_func_getgroups_works="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) ac_cv_func_getgroups_works="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             ac_cv_func_getgroups_works="guessing no" ;;
           esac
          ])
       ])
@@ -93,10 +93,10 @@ AC_DEFUN([gl_FUNC_GETGROUPS],
           [gl_cv_func_getgroups_works=yes],
           [gl_cv_func_getgroups_works=no],
           [case "$host_os" in
-                     # Guess yes on glibc systems.
-             *-gnu*) gl_cv_func_getgroups_works="guessing yes" ;;
-                     # If we don't know, assume the worst.
-             *)      gl_cv_func_getgroups_works="guessing no" ;;
+                            # Guess yes on glibc systems.
+             *-gnu* | gnu*) gl_cv_func_getgroups_works="guessing yes" ;;
+                            # If we don't know, assume the worst.
+             *)             gl_cv_func_getgroups_works="guessing no" ;;
            esac
           ])])
       case "$gl_cv_func_getgroups_works" in
diff --git a/m4/gettimeofday.m4 b/m4/gettimeofday.m4
index efa114dfaf..5996065504 100644
--- a/m4/gettimeofday.m4
+++ b/m4/gettimeofday.m4
@@ -1,4 +1,4 @@
-# serial 24
+# serial 25
 
 # Copyright (C) 2001-2003, 2005, 2007, 2009-2017 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -103,12 +103,12 @@ AC_DEFUN([gl_FUNC_GETTIMEOFDAY_CLOBBER],
      [gl_cv_func_gettimeofday_clobber=yes],
      [# When cross-compiling:
       case "$host_os" in
-                # Guess all is fine on glibc systems.
-        *-gnu*) gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                # Guess no on native Windows.
-        mingw*) gl_cv_func_gettimeofday_clobber="guessing no" ;;
-                # If we don't know, assume the worst.
-        *)      gl_cv_func_gettimeofday_clobber="guessing yes" ;;
+                       # Guess all is fine on glibc systems.
+        *-gnu* | gnu*) gl_cv_func_gettimeofday_clobber="guessing no" ;;
+                       # Guess no on native Windows.
+        mingw*)        gl_cv_func_gettimeofday_clobber="guessing no" ;;
+                       # If we don't know, assume the worst.
+        *)             gl_cv_func_gettimeofday_clobber="guessing yes" ;;
       esac
      ])])
 
diff --git a/m4/hypot.m4 b/m4/hypot.m4
index 0684792911..a7ac9347f3 100644
--- a/m4/hypot.m4
+++ b/m4/hypot.m4
@@ -1,4 +1,4 @@
-# hypot.m4 serial 5
+# hypot.m4 serial 6
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -55,12 +55,12 @@ int main (int argc, char *argv[])
             [gl_cv_func_hypot_ieee=yes],
             [gl_cv_func_hypot_ieee=no],
             [case "$host_os" in
-                       # Guess yes on glibc systems.
-               *-gnu*) gl_cv_func_hypot_ieee="guessing yes" ;;
-                       # Guess yes on native Windows.
-               mingw*) gl_cv_func_hypot_ieee="guessing yes" ;;
-                       # If we don't know, assume the worst.
-               *)      gl_cv_func_hypot_ieee="guessing no" ;;
+                              # Guess yes on glibc systems.
+               *-gnu* | gnu*) gl_cv_func_hypot_ieee="guessing yes" ;;
+                              # Guess yes on native Windows.
+               mingw*)        gl_cv_func_hypot_ieee="guessing yes" ;;
+                              # If we don't know, assume the worst.
+               *)             gl_cv_func_hypot_ieee="guessing no" ;;
              esac
             ])
           LIBS="$save_LIBS"
diff --git a/m4/hypotf.m4 b/m4/hypotf.m4
index d012cd822f..4df9324efe 100644
--- a/m4/hypotf.m4
+++ b/m4/hypotf.m4
@@ -1,4 +1,4 @@
-# hypotf.m4 serial 6
+# hypotf.m4 serial 7
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -71,12 +71,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_hypotf_ieee=yes],
               [gl_cv_func_hypotf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_hypotf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_hypotf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_hypotf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_hypotf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_hypotf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_hypotf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/hypotl.m4 b/m4/hypotl.m4
index 64f7af21cf..69bd7d1be3 100644
--- a/m4/hypotl.m4
+++ b/m4/hypotl.m4
@@ -1,4 +1,4 @@
-# hypotl.m4 serial 7
+# hypotl.m4 serial 8
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -71,12 +71,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_hypotl_ieee=yes],
               [gl_cv_func_hypotl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_hypotl_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_hypotl_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_hypotl_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_hypotl_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_hypotl_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_hypotl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/link-follow.m4 b/m4/link-follow.m4
index 587b03ff04..dbab78169a 100644
--- a/m4/link-follow.m4
+++ b/m4/link-follow.m4
@@ -1,4 +1,4 @@
-# serial 19
+# serial 20
 dnl Run a program to determine whether link(2) follows symlinks.
 dnl Set LINK_FOLLOWS_SYMLINKS accordingly.
 
@@ -86,10 +86,10 @@ AC_DEFUN([gl_FUNC_LINK_FOLLOWS_SYMLINK],
             dnl The past results are "yes" on Mac OS X, FreeBSD, NetBSD,
             dnl OpenBSD, Minix, AIX, HP-UX, OSF/1, and "no" on Linux, Cygwin.
             case "$host_os" in
-                           # On glibc/Linux we know the result.
-              linux*-gnu*) gl_cv_func_link_follows_symlink="guessing no" ;;
-                           # Otherwise, we don't know.
-              *)           gl_cv_func_link_follows_symlink=unknown ;;
+                                  # On glibc/Linux we know the result.
+              linux*-gnu* | gnu*) gl_cv_func_link_follows_symlink="guessing no" ;;
+                                  # Otherwise, we don't know.
+              *)                  gl_cv_func_link_follows_symlink=unknown ;;
             esac
            ])
          rm -f conftest.file conftest.sym conftest.hard
diff --git a/m4/link.m4 b/m4/link.m4
index 021c30140e..5b44f55a4a 100644
--- a/m4/link.m4
+++ b/m4/link.m4
@@ -1,4 +1,4 @@
-# link.m4 serial 8
+# link.m4 serial 9
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -39,10 +39,10 @@ AC_DEFUN([gl_FUNC_LINK],
            ]])],
          [gl_cv_func_link_works=yes], [gl_cv_func_link_works=no],
          [case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_link_works="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_link_works="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_link_works="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_link_works="guessing no" ;;
           esac
          ])
        rm -f conftest.a conftest.b conftest.lnk])
diff --git a/m4/linkat.m4 b/m4/linkat.m4
index 31d87289a3..38a96134ac 100644
--- a/m4/linkat.m4
+++ b/m4/linkat.m4
@@ -1,4 +1,4 @@
-# serial 7
+# serial 8
 # See if we need to provide linkat replacement.
 
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
@@ -98,8 +98,8 @@ AC_DEFUN([gl_FUNC_LINKAT],
          [gl_cv_func_linkat_slash=no],
          [# Guess yes on glibc systems, no otherwise.
           case "$host_os" in
-            *-gnu*) gl_cv_func_linkat_slash="guessing yes";;
-            *)      gl_cv_func_linkat_slash="guessing no";;
+            *-gnu* | gnu*) gl_cv_func_linkat_slash="guessing yes";;
+            *)             gl_cv_func_linkat_slash="guessing no";;
           esac
          ])
        rm -rf conftest.a conftest.b conftest.c conftest.d conftest.e conftest.s])
diff --git a/m4/log.m4 b/m4/log.m4
index 61902ea7c4..d830f092fe 100644
--- a/m4/log.m4
+++ b/m4/log.m4
@@ -1,4 +1,4 @@
-# log.m4 serial 6
+# log.m4 serial 7
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -58,12 +58,12 @@ int main (int argc, char *argv[])
             [gl_cv_func_log_ieee=yes],
             [gl_cv_func_log_ieee=no],
             [case "$host_os" in
-                       # Guess yes on glibc systems.
-               *-gnu*) gl_cv_func_log_ieee="guessing yes" ;;
-                       # Guess yes on native Windows.
-               mingw*) gl_cv_func_log_ieee="guessing yes" ;;
-                       # If we don't know, assume the worst.
-               *)      gl_cv_func_log_ieee="guessing no" ;;
+                              # Guess yes on glibc systems.
+               *-gnu* | gnu*) gl_cv_func_log_ieee="guessing yes" ;;
+                              # Guess yes on native Windows.
+               mingw*)        gl_cv_func_log_ieee="guessing yes" ;;
+                              # If we don't know, assume the worst.
+               *)             gl_cv_func_log_ieee="guessing no" ;;
              esac
             ])
           LIBS="$save_LIBS"
diff --git a/m4/log10.m4 b/m4/log10.m4
index a384481284..a5a9592d6d 100644
--- a/m4/log10.m4
+++ b/m4/log10.m4
@@ -1,4 +1,4 @@
-# log10.m4 serial 6
+# log10.m4 serial 7
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -58,12 +58,12 @@ int main (int argc, char *argv[])
             [gl_cv_func_log10_ieee=yes],
             [gl_cv_func_log10_ieee=no],
             [case "$host_os" in
-                       # Guess yes on glibc systems.
-               *-gnu*) gl_cv_func_log10_ieee="guessing yes" ;;
-                       # Guess yes on native Windows.
-               mingw*) gl_cv_func_log10_ieee="guessing yes" ;;
-                       # If we don't know, assume the worst.
-               *)      gl_cv_func_log10_ieee="guessing no" ;;
+                              # Guess yes on glibc systems.
+               *-gnu* | gnu*) gl_cv_func_log10_ieee="guessing yes" ;;
+                              # Guess yes on native Windows.
+               mingw*)        gl_cv_func_log10_ieee="guessing yes" ;;
+                              # If we don't know, assume the worst.
+               *)             gl_cv_func_log10_ieee="guessing no" ;;
              esac
             ])
           LIBS="$save_LIBS"
diff --git a/m4/log10f.m4 b/m4/log10f.m4
index 699e3a1592..7270adde87 100644
--- a/m4/log10f.m4
+++ b/m4/log10f.m4
@@ -1,4 +1,4 @@
-# log10f.m4 serial 8
+# log10f.m4 serial 9
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -68,12 +68,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_log10f_ieee=yes],
               [gl_cv_func_log10f_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_log10f_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_log10f_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_log10f_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_log10f_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_log10f_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_log10f_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/log1p.m4 b/m4/log1p.m4
index ae8fc53e62..b5ec93769b 100644
--- a/m4/log1p.m4
+++ b/m4/log1p.m4
@@ -1,4 +1,4 @@
-# log1p.m4 serial 4
+# log1p.m4 serial 5
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -52,12 +52,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_log1p_ieee=yes],
               [gl_cv_func_log1p_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_log1p_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_log1p_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_log1p_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_log1p_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_log1p_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_log1p_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/log1pf.m4 b/m4/log1pf.m4
index 8c8a714d09..fe75102963 100644
--- a/m4/log1pf.m4
+++ b/m4/log1pf.m4
@@ -1,4 +1,4 @@
-# log1pf.m4 serial 4
+# log1pf.m4 serial 5
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -61,12 +61,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_log1pf_ieee=yes],
               [gl_cv_func_log1pf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_log1pf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_log1pf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_log1pf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_log1pf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_log1pf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_log1pf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/log1pl.m4 b/m4/log1pl.m4
index 519507f44f..18fd48b9d6 100644
--- a/m4/log1pl.m4
+++ b/m4/log1pl.m4
@@ -1,4 +1,4 @@
-# log1pl.m4 serial 4
+# log1pl.m4 serial 5
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -52,12 +52,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_log1pl_ieee=yes],
               [gl_cv_func_log1pl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_log1pl_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_log1pl_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_log1pl_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_log1pl_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_log1pl_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_log1pl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/log2.m4 b/m4/log2.m4
index e20fc09905..cf46b39d43 100644
--- a/m4/log2.m4
+++ b/m4/log2.m4
@@ -1,4 +1,4 @@
-# log2.m4 serial 6
+# log2.m4 serial 7
 dnl Copyright (C) 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -79,12 +79,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_log2_ieee=yes],
               [gl_cv_func_log2_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_log2_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_log2_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_log2_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_log2_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_log2_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_log2_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/log2f.m4 b/m4/log2f.m4
index 0dbaedbd48..6c0f58f71c 100644
--- a/m4/log2f.m4
+++ b/m4/log2f.m4
@@ -1,4 +1,4 @@
-# log2f.m4 serial 6
+# log2f.m4 serial 7
 dnl Copyright (C) 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -80,12 +80,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_log2f_ieee=yes],
               [gl_cv_func_log2f_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_log2f_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_log2f_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_log2f_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_log2f_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_log2f_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_log2f_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/logf.m4 b/m4/logf.m4
index 096c679fb2..b8092b8653 100644
--- a/m4/logf.m4
+++ b/m4/logf.m4
@@ -1,4 +1,4 @@
-# logf.m4 serial 8
+# logf.m4 serial 9
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -68,12 +68,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_logf_ieee=yes],
               [gl_cv_func_logf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_logf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_logf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_logf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_logf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_logf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_logf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/lstat.m4 b/m4/lstat.m4
index 6ba18cec57..02664cf11a 100644
--- a/m4/lstat.m4
+++ b/m4/lstat.m4
@@ -1,4 +1,4 @@
-# serial 30
+# serial 31
 
 # Copyright (C) 1997-2001, 2003-2017 Free Software Foundation, Inc.
 #
@@ -53,7 +53,7 @@ AC_DEFUN([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK],
        [gl_cv_func_lstat_dereferences_slashed_symlink=yes],
        [gl_cv_func_lstat_dereferences_slashed_symlink=no],
        [case "$host_os" in
-          *-gnu*)
+          *-gnu* | gnu*)
             # Guess yes on glibc systems.
             gl_cv_func_lstat_dereferences_slashed_symlink="guessing yes" ;;
           mingw*)
diff --git a/m4/malloc.m4 b/m4/malloc.m4
index 5e6a83a67f..d312a2561a 100644
--- a/m4/malloc.m4
+++ b/m4/malloc.m4
@@ -1,4 +1,4 @@
-# malloc.m4 serial 15
+# malloc.m4 serial 16
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -32,7 +32,7 @@ AC_DEFUN([_AC_FUNC_MALLOC_IF],
        [ac_cv_func_malloc_0_nonnull=no],
        [case "$host_os" in
           # Guess yes on platforms where we know the result.
-          *-gnu* | freebsd* | netbsd* | openbsd* \
+          *-gnu* | gnu* | freebsd* | netbsd* | openbsd* \
           | hpux* | solaris* | cygwin* | mingw*)
             ac_cv_func_malloc_0_nonnull=yes ;;
           # If we don't know, assume the worst.
diff --git a/m4/mbrlen.m4 b/m4/mbrlen.m4
index cd579a2908..6ed117abbf 100644
--- a/m4/mbrlen.m4
+++ b/m4/mbrlen.m4
@@ -1,4 +1,4 @@
-# mbrlen.m4 serial 9  -*- coding: utf-8 -*-
+# mbrlen.m4 serial 10  -*- coding: utf-8 -*-
 dnl Copyright (C) 2008, 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -240,10 +240,9 @@ AC_DEFUN([gl_MBRLEN_EMPTY_INPUT],
       dnl is present.
 changequote(,)dnl
       case "$host_os" in
-                     # Guess no on AIX and glibc systems.
-        aix* | *-gnu*)
-                    gl_cv_func_mbrlen_empty_input="guessing no" ;;
-        *)          gl_cv_func_mbrlen_empty_input="guessing yes" ;;
+                              # Guess no on AIX and glibc systems.
+        aix* | *-gnu* | gnu*) gl_cv_func_mbrlen_empty_input="guessing no" ;;
+        *)                    gl_cv_func_mbrlen_empty_input="guessing yes" ;;
       esac
 changequote([,])dnl
       AC_RUN_IFELSE(
diff --git a/m4/mbrtowc.m4 b/m4/mbrtowc.m4
index 216594eb94..d2024c4498 100644
--- a/m4/mbrtowc.m4
+++ b/m4/mbrtowc.m4
@@ -1,4 +1,4 @@
-# mbrtowc.m4 serial 29  -*- coding: utf-8 -*-
+# mbrtowc.m4 serial 30  -*- coding: utf-8 -*-
 dnl Copyright (C) 2001-2002, 2004-2005, 2008-2017 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@@ -563,12 +563,11 @@ AC_DEFUN([gl_MBRTOWC_EMPTY_INPUT],
       dnl is present.
 changequote(,)dnl
       case "$host_os" in
-                    # Guess no on AIX and glibc systems.
-        aix* | *-gnu*)
-                    gl_cv_func_mbrtowc_empty_input="guessing no" ;;
-                    # Guess yes on native Windows.
-        mingw*)     gl_cv_func_mbrtowc_empty_input="guessing yes" ;;
-        *)          gl_cv_func_mbrtowc_empty_input="guessing yes" ;;
+                              # Guess no on AIX and glibc systems.
+        aix* | *-gnu* | gnu*) gl_cv_func_mbrtowc_empty_input="guessing no" ;;
+                              # Guess yes on native Windows.
+        mingw*)               gl_cv_func_mbrtowc_empty_input="guessing yes" ;;
+        *)                    gl_cv_func_mbrtowc_empty_input="guessing yes" ;;
       esac
 changequote([,])dnl
       AC_RUN_IFELSE(
diff --git a/m4/mkdir.m4 b/m4/mkdir.m4
index fa15b15789..e5c4e89e56 100644
--- a/m4/mkdir.m4
+++ b/m4/mkdir.m4
@@ -1,4 +1,4 @@
-# serial 12
+# serial 13
 
 # Copyright (C) 2001, 2003-2004, 2006, 2008-2017 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -23,19 +23,19 @@ AC_DEFUN([gl_FUNC_MKDIR],
       [gl_cv_func_mkdir_trailing_slash_works=yes],
       [gl_cv_func_mkdir_trailing_slash_works=no],
       [case "$host_os" in
-                 # Guess yes on glibc systems.
-         *-gnu*) gl_cv_func_mkdir_trailing_slash_works="guessing yes" ;;
-                 # Guess yes on MSVC, no on mingw.
-         mingw*) AC_EGREP_CPP([Known], [
+                        # Guess yes on glibc systems.
+         *-gnu* | gnu*) gl_cv_func_mkdir_trailing_slash_works="guessing yes" ;;
+                        # Guess yes on MSVC, no on mingw.
+         mingw*)        AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                   ],
-                   [gl_cv_func_mkdir_trailing_slash_works="guessing yes"],
-                   [gl_cv_func_mkdir_trailing_slash_works="guessing no"])
-                 ;;
-                 # If we don't know, assume the worst.
-         *)      gl_cv_func_mkdir_trailing_slash_works="guessing no" ;;
+                          ],
+                          [gl_cv_func_mkdir_trailing_slash_works="guessing yes"],
+                          [gl_cv_func_mkdir_trailing_slash_works="guessing no"])
+                        ;;
+                        # If we don't know, assume the worst.
+         *)             gl_cv_func_mkdir_trailing_slash_works="guessing no" ;;
        esac
       ])
     rm -rf conftest.dir
@@ -58,12 +58,12 @@ AC_DEFUN([gl_FUNC_MKDIR],
       [gl_cv_func_mkdir_trailing_dot_works=yes],
       [gl_cv_func_mkdir_trailing_dot_works=no],
       [case "$host_os" in
-                 # Guess yes on glibc systems.
-         *-gnu*) gl_cv_func_mkdir_trailing_dot_works="guessing yes" ;;
-                 # Guess no on native Windows.
-         mingw*) gl_cv_func_mkdir_trailing_dot_works="guessing no" ;;
-                 # If we don't know, assume the worst.
-         *)      gl_cv_func_mkdir_trailing_dot_works="guessing no" ;;
+                        # Guess yes on glibc systems.
+         *-gnu* | gnu*) gl_cv_func_mkdir_trailing_dot_works="guessing yes" ;;
+                        # Guess no on native Windows.
+         mingw*)        gl_cv_func_mkdir_trailing_dot_works="guessing no" ;;
+                        # If we don't know, assume the worst.
+         *)             gl_cv_func_mkdir_trailing_dot_works="guessing no" ;;
        esac
       ])
     rm -rf conftest.dir
diff --git a/m4/mkfifo.m4 b/m4/mkfifo.m4
index f2516a9d65..d59c86ac3d 100644
--- a/m4/mkfifo.m4
+++ b/m4/mkfifo.m4
@@ -1,4 +1,4 @@
-# serial 4
+# serial 5
 # See if we need to provide mkfifo replacement.
 
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
@@ -39,10 +39,10 @@ AC_DEFUN([gl_FUNC_MKFIFO],
            ]])],
          [gl_cv_func_mkfifo_works=yes], [gl_cv_func_mkfifo_works=no],
          [case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_mkfifo_works="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_mkfifo_works="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_mkfifo_works="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_mkfifo_works="guessing no" ;;
           esac
          ])
        rm -f conftest.tmp conftest.lnk])
diff --git a/m4/mknod.m4 b/m4/mknod.m4
index 98ecea2967..70ac260f22 100644
--- a/m4/mknod.m4
+++ b/m4/mknod.m4
@@ -1,4 +1,4 @@
-# serial 5
+# serial 6
 # See if we need to provide mknod replacement.
 
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
@@ -43,10 +43,10 @@ AC_DEFUN([gl_FUNC_MKNOD],
           fi
           gl_cv_func_mknod_works=no],
          [case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_mknod_works="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_mknod_works="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_mknod_works="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_mknod_works="guessing no" ;;
           esac
          ])
        rm -f conftest.fifo])
diff --git a/m4/mkstemp.m4 b/m4/mkstemp.m4
index 82f02864f3..2f9196a0e1 100644
--- a/m4/mkstemp.m4
+++ b/m4/mkstemp.m4
@@ -1,4 +1,4 @@
-#serial 24
+#serial 25
 
 # Copyright (C) 2001, 2003-2007, 2009-2017 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -57,12 +57,12 @@ AC_DEFUN([gl_FUNC_MKSTEMP],
           [gl_cv_func_working_mkstemp=yes],
           [gl_cv_func_working_mkstemp=no],
           [case "$host_os" in
-                     # Guess yes on glibc systems.
-             *-gnu*) gl_cv_func_working_mkstemp="guessing yes" ;;
-                     # Guess no on native Windows.
-             mingw*) gl_cv_func_working_mkstemp="guessing no" ;;
-                     # If we don't know, assume the worst.
-             *)      gl_cv_func_working_mkstemp="guessing no" ;;
+                            # Guess yes on glibc systems.
+             *-gnu* | gnu*) gl_cv_func_working_mkstemp="guessing yes" ;;
+                            # Guess no on native Windows.
+             mingw*)        gl_cv_func_working_mkstemp="guessing no" ;;
+                            # If we don't know, assume the worst.
+             *)             gl_cv_func_working_mkstemp="guessing no" ;;
            esac
           ])
         rm -rf conftest.mkstemp
diff --git a/m4/modf.m4 b/m4/modf.m4
index 7cb8c3d60f..a9986e9b31 100644
--- a/m4/modf.m4
+++ b/m4/modf.m4
@@ -1,4 +1,4 @@
-# modf.m4 serial 4
+# modf.m4 serial 5
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -61,19 +61,19 @@ int main (int argc, char *argv[])
             [gl_cv_func_modf_ieee=yes],
             [gl_cv_func_modf_ieee=no],
             [case "$host_os" in
-                       # Guess yes on glibc systems.
-               *-gnu*) gl_cv_func_modf_ieee="guessing yes" ;;
-                       # Guess yes on MSVC, no on mingw.
-               mingw*) AC_EGREP_CPP([Known], [
+                              # Guess yes on glibc systems.
+               *-gnu* | gnu*) gl_cv_func_modf_ieee="guessing yes" ;;
+                              # Guess yes on MSVC, no on mingw.
+               mingw*)        AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                         ],
-                         [gl_cv_func_modf_ieee="guessing yes"],
-                         [gl_cv_func_modf_ieee="guessing no"])
-                       ;;
-                       # If we don't know, assume the worst.
-               *)      gl_cv_func_modf_ieee="guessing no" ;;
+                                ],
+                                [gl_cv_func_modf_ieee="guessing yes"],
+                                [gl_cv_func_modf_ieee="guessing no"])
+                              ;;
+                              # If we don't know, assume the worst.
+               *)             gl_cv_func_modf_ieee="guessing no" ;;
              esac
             ])
           LIBS="$save_LIBS"
diff --git a/m4/modff.m4 b/m4/modff.m4
index e32d5372eb..a98c1917db 100644
--- a/m4/modff.m4
+++ b/m4/modff.m4
@@ -1,4 +1,4 @@
-# modff.m4 serial 6
+# modff.m4 serial 7
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -69,19 +69,19 @@ int main (int argc, char *argv[])
               [gl_cv_func_modff_ieee=yes],
               [gl_cv_func_modff_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_modff_ieee="guessing yes" ;;
-                         # Guess yes on MSVC, no on mingw.
-                 mingw*) AC_EGREP_CPP([Known], [
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_modff_ieee="guessing yes" ;;
+                                # Guess yes on MSVC, no on mingw.
+                 mingw*)        AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                           ],
-                           [gl_cv_func_modff_ieee="guessing yes"],
-                           [gl_cv_func_modff_ieee="guessing no"])
-                         ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_modff_ieee="guessing no" ;;
+                                  ],
+                                  [gl_cv_func_modff_ieee="guessing yes"],
+                                  [gl_cv_func_modff_ieee="guessing no"])
+                                ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_modff_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/modfl.m4 b/m4/modfl.m4
index 152109f77a..0e4e8e04ff 100644
--- a/m4/modfl.m4
+++ b/m4/modfl.m4
@@ -1,4 +1,4 @@
-# modfl.m4 serial 4
+# modfl.m4 serial 5
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -63,19 +63,19 @@ int main (int argc, char *argv[])
               [gl_cv_func_modfl_ieee=yes],
               [gl_cv_func_modfl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_modfl_ieee="guessing yes" ;;
-                         # Guess yes on MSVC, no on mingw.
-                 mingw*) AC_EGREP_CPP([Known], [
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_modfl_ieee="guessing yes" ;;
+                                # Guess yes on MSVC, no on mingw.
+                 mingw*)        AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                           ],
-                           [gl_cv_func_modfl_ieee="guessing yes"],
-                           [gl_cv_func_modfl_ieee="guessing no"])
-                         ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_modfl_ieee="guessing no" ;;
+                                  ],
+                                  [gl_cv_func_modfl_ieee="guessing yes"],
+                                  [gl_cv_func_modfl_ieee="guessing no"])
+                                ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_modfl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/printf.m4 b/m4/printf.m4
index 3b167ecb26..99c91a0fe1 100644
--- a/m4/printf.m4
+++ b/m4/printf.m4
@@ -1,4 +1,4 @@
-# printf.m4 serial 57
+# printf.m4 serial 58
 dnl Copyright (C) 2003, 2007-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -61,7 +61,7 @@ int main ()
          case "$host_os" in
 changequote(,)dnl
                                  # Guess yes on glibc systems.
-           *-gnu*)               gl_cv_func_printf_sizes_c99="guessing yes";;
+           *-gnu* | gnu*)        gl_cv_func_printf_sizes_c99="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_printf_sizes_c99="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_printf_sizes_c99="guessing yes";;
@@ -234,7 +234,7 @@ int main ()
          case "$host_os" in
 changequote(,)dnl
                                  # Guess yes on glibc systems.
-           *-gnu*)               gl_cv_func_printf_infinite="guessing yes";;
+           *-gnu* | gnu*)        gl_cv_func_printf_infinite="guessing yes";;
                                  # Guess yes on FreeBSD >= 6.
            freebsd[1-5].*)       gl_cv_func_printf_infinite="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_printf_infinite="guessing yes";;
@@ -449,7 +449,7 @@ int main ()
                  case "$host_os" in
 changequote(,)dnl
                                          # Guess yes on glibc systems.
-                   *-gnu*)               gl_cv_func_printf_infinite_long_double="guessing yes";;
+                   *-gnu* | gnu*)        gl_cv_func_printf_infinite_long_double="guessing yes";;
                                          # Guess yes on FreeBSD >= 6.
                    freebsd[1-5].*)       gl_cv_func_printf_infinite_long_double="guessing no";;
                    freebsd* | kfreebsd*) gl_cv_func_printf_infinite_long_double="guessing yes";;
@@ -554,7 +554,7 @@ int main ()
         [
          case "$host_os" in
                                  # Guess yes on glibc >= 2.5 systems.
-           *-gnu*)
+           *-gnu* | gnu*)
              AC_EGREP_CPP([BZ2908], [
                #include <features.h>
                #ifdef __GNU_LIBRARY__
@@ -613,7 +613,7 @@ int main ()
          case "$host_os" in
 changequote(,)dnl
                                  # Guess yes on glibc systems.
-           *-gnu*)               gl_cv_func_printf_directive_f="guessing yes";;
+           *-gnu* | gnu*)        gl_cv_func_printf_directive_f="guessing yes";;
                                  # Guess yes on FreeBSD >= 6.
            freebsd[1-5].*)       gl_cv_func_printf_directive_f="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_printf_directive_f="guessing yes";;
@@ -935,14 +935,14 @@ int main ()
         [
 changequote(,)dnl
          case "$host_os" in
-                   # Guess yes on glibc systems.
-           *-gnu*) gl_cv_func_printf_flag_zero="guessing yes";;
-                   # Guess yes on BeOS.
-           beos*)  gl_cv_func_printf_flag_zero="guessing yes";;
-                   # Guess no on native Windows.
-           mingw*) gl_cv_func_printf_flag_zero="guessing no";;
-                   # If we don't know, assume the worst.
-           *)      gl_cv_func_printf_flag_zero="guessing no";;
+                          # Guess yes on glibc systems.
+           *-gnu* | gnu*) gl_cv_func_printf_flag_zero="guessing yes";;
+                          # Guess yes on BeOS.
+           beos*)         gl_cv_func_printf_flag_zero="guessing yes";;
+                          # Guess no on native Windows.
+           mingw*)        gl_cv_func_printf_flag_zero="guessing no";;
+                          # If we don't know, assume the worst.
+           *)             gl_cv_func_printf_flag_zero="guessing no";;
          esac
 changequote([,])dnl
         ])
@@ -1095,28 +1095,28 @@ changequote([,])dnl
       if test "$gl_cv_func_printf_enomem" = "guessing no"; then
 changequote(,)dnl
         case "$host_os" in
-                    # Guess yes on glibc systems.
-          *-gnu*)   gl_cv_func_printf_enomem="guessing yes";;
-                    # Guess yes on Solaris.
-          solaris*) gl_cv_func_printf_enomem="guessing yes";;
-                    # Guess yes on AIX.
-          aix*)     gl_cv_func_printf_enomem="guessing yes";;
-                    # Guess yes on HP-UX/hppa.
-          hpux*)    case "$host_cpu" in
-                      hppa*) gl_cv_func_printf_enomem="guessing yes";;
-                      *)     gl_cv_func_printf_enomem="guessing no";;
-                    esac
-                    ;;
-                    # Guess yes on IRIX.
-          irix*)    gl_cv_func_printf_enomem="guessing yes";;
-                    # Guess yes on OSF/1.
-          osf*)     gl_cv_func_printf_enomem="guessing yes";;
-                    # Guess yes on BeOS.
-          beos*)    gl_cv_func_printf_enomem="guessing yes";;
-                    # Guess yes on Haiku.
-          haiku*)   gl_cv_func_printf_enomem="guessing yes";;
-                    # If we don't know, assume the worst.
-          *)        gl_cv_func_printf_enomem="guessing no";;
+                         # Guess yes on glibc systems.
+          *-gnu* | gnu*) gl_cv_func_printf_enomem="guessing yes";;
+                         # Guess yes on Solaris.
+          solaris*)      gl_cv_func_printf_enomem="guessing yes";;
+                         # Guess yes on AIX.
+          aix*)          gl_cv_func_printf_enomem="guessing yes";;
+                         # Guess yes on HP-UX/hppa.
+          hpux*)         case "$host_cpu" in
+                           hppa*) gl_cv_func_printf_enomem="guessing yes";;
+                           *)     gl_cv_func_printf_enomem="guessing no";;
+                         esac
+                         ;;
+                         # Guess yes on IRIX.
+          irix*)         gl_cv_func_printf_enomem="guessing yes";;
+                         # Guess yes on OSF/1.
+          osf*)          gl_cv_func_printf_enomem="guessing yes";;
+                         # Guess yes on BeOS.
+          beos*)         gl_cv_func_printf_enomem="guessing yes";;
+                         # Guess yes on Haiku.
+          haiku*)        gl_cv_func_printf_enomem="guessing yes";;
+                         # If we don't know, assume the worst.
+          *)             gl_cv_func_printf_enomem="guessing no";;
         esac
 changequote([,])dnl
       fi
@@ -1176,7 +1176,7 @@ int main ()
 changequote(,)dnl
          case "$host_os" in
                                  # Guess yes on glibc systems.
-           *-gnu*)               gl_cv_func_snprintf_truncation_c99="guessing yes";;
+           *-gnu* | gnu*)        gl_cv_func_snprintf_truncation_c99="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_snprintf_truncation_c99="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_snprintf_truncation_c99="guessing yes";;
@@ -1276,7 +1276,7 @@ int main ()
         [case "$host_os" in
 changequote(,)dnl
                                  # Guess yes on glibc systems.
-           *-gnu*)               gl_cv_func_snprintf_retval_c99="guessing yes";;
+           *-gnu* | gnu*)        gl_cv_func_snprintf_retval_c99="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_snprintf_retval_c99="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_snprintf_retval_c99="guessing yes";;
@@ -1366,7 +1366,7 @@ int main ()
 changequote(,)dnl
          case "$host_os" in
                                  # Guess yes on glibc systems.
-           *-gnu*)               gl_cv_func_snprintf_directive_n="guessing yes";;
+           *-gnu* | gnu*)        gl_cv_func_snprintf_directive_n="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_snprintf_directive_n="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_snprintf_directive_n="guessing yes";;
@@ -1516,7 +1516,7 @@ int main()
 changequote(,)dnl
          case "$host_os" in
                                  # Guess yes on glibc systems.
-           *-gnu*)               gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
+           *-gnu* | gnu*)        gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
                                  # Guess yes on FreeBSD >= 5.
            freebsd[1-4].*)       gl_cv_func_vsnprintf_zerosize_c99="guessing no";;
            freebsd* | kfreebsd*) gl_cv_func_vsnprintf_zerosize_c99="guessing yes";;
diff --git a/m4/pselect.m4 b/m4/pselect.m4
index eb1ad115cc..fc2aaf05d6 100644
--- a/m4/pselect.m4
+++ b/m4/pselect.m4
@@ -1,4 +1,4 @@
-# pselect.m4 serial 4
+# pselect.m4 serial 6
 dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -51,10 +51,10 @@ AC_DEFUN([gl_FUNC_PSELECT],
       [gl_cv_func_pselect_detects_ebadf=no],
           [
            case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_pselect_detects_ebadf="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_pselect_detects_ebadf="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_pselect_detects_ebadf="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_pselect_detects_ebadf="guessing no" ;;
            esac
           ])
       ])
diff --git a/m4/ptsname.m4 b/m4/ptsname.m4
index a8fb6c87df..23b411f2e8 100644
--- a/m4/ptsname.m4
+++ b/m4/ptsname.m4
@@ -1,4 +1,4 @@
-# ptsname.m4 serial 4
+# ptsname.m4 serial 5
 dnl Copyright (C) 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -26,10 +26,10 @@ AC_DEFUN([gl_FUNC_PTSNAME],
          [gl_cv_func_ptsname_sets_errno=yes],
          [gl_cv_func_ptsname_sets_errno=no],
          [case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_ptsname_sets_errno="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_ptsname_sets_errno="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_ptsname_sets_errno="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_ptsname_sets_errno="guessing no" ;;
           esac
          ])])
     case $gl_cv_func_ptsname_sets_errno in
diff --git a/m4/putenv.m4 b/m4/putenv.m4
index 08ae41697a..d4a8840bfa 100644
--- a/m4/putenv.m4
+++ b/m4/putenv.m4
@@ -1,4 +1,4 @@
-# putenv.m4 serial 21
+# putenv.m4 serial 22
 dnl Copyright (C) 2002-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -34,12 +34,12 @@ AC_DEFUN([gl_FUNC_PUTENV],
              gl_cv_func_svid_putenv=no,
              dnl When crosscompiling, assume putenv is broken.
              [case "$host_os" in
-                        # Guess yes on glibc systems.
-                *-gnu*) gl_cv_func_svid_putenv="guessing yes" ;;
-                        # Guess no on native Windows.
-                mingw*) gl_cv_func_svid_putenv="guessing no" ;;
-                        # If we don't know, assume the worst.
-                *)      gl_cv_func_svid_putenv="guessing no" ;;
+                               # Guess yes on glibc systems.
+                *-gnu* | gnu*) gl_cv_func_svid_putenv="guessing yes" ;;
+                               # Guess no on native Windows.
+                mingw*)        gl_cv_func_svid_putenv="guessing no" ;;
+                               # If we don't know, assume the worst.
+                *)             gl_cv_func_svid_putenv="guessing no" ;;
               esac
              ])
    ])
diff --git a/m4/readlink.m4 b/m4/readlink.m4
index d3ba0ad421..0444328b97 100644
--- a/m4/readlink.m4
+++ b/m4/readlink.m4
@@ -1,4 +1,4 @@
-# readlink.m4 serial 12
+# readlink.m4 serial 13
 dnl Copyright (C) 2003, 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -34,10 +34,10 @@ AC_DEFUN([gl_FUNC_READLINK],
       return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],
          [gl_cv_func_readlink_works=yes], [gl_cv_func_readlink_works=no],
          [case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_readlink_works="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_readlink_works="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_readlink_works="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_readlink_works="guessing no" ;;
           esac
          ])
       rm -f conftest.link conftest.lnk2])
diff --git a/m4/realloc.m4 b/m4/realloc.m4
index dbac45f121..bf19a3cacc 100644
--- a/m4/realloc.m4
+++ b/m4/realloc.m4
@@ -1,4 +1,4 @@
-# realloc.m4 serial 14
+# realloc.m4 serial 15
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -32,7 +32,7 @@ AC_DEFUN([_AC_FUNC_REALLOC_IF],
        [ac_cv_func_realloc_0_nonnull=no],
        [case "$host_os" in
           # Guess yes on platforms where we know the result.
-          *-gnu* | freebsd* | netbsd* | openbsd* \
+          *-gnu* | gnu* | freebsd* | netbsd* | openbsd* \
           | hpux* | solaris* | cygwin* | mingw*)
             ac_cv_func_realloc_0_nonnull=yes ;;
           # If we don't know, assume the worst.
diff --git a/m4/remainder.m4 b/m4/remainder.m4
index f9a9177513..129334ca2b 100644
--- a/m4/remainder.m4
+++ b/m4/remainder.m4
@@ -1,4 +1,4 @@
-# remainder.m4 serial 5
+# remainder.m4 serial 6
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -92,12 +92,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_remainder_ieee=yes],
               [gl_cv_func_remainder_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_remainder_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_remainder_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_remainder_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_remainder_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_remainder_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_remainder_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/remainderf.m4 b/m4/remainderf.m4
index fcce7b0808..fb7a6ec566 100644
--- a/m4/remainderf.m4
+++ b/m4/remainderf.m4
@@ -1,4 +1,4 @@
-# remainderf.m4 serial 9
+# remainderf.m4 serial 10
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -95,12 +95,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_remainderf_ieee=yes],
               [gl_cv_func_remainderf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_remainderf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_remainderf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_remainderf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_remainderf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_remainderf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_remainderf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/remainderl.m4 b/m4/remainderl.m4
index 294ec093d2..c65092a382 100644
--- a/m4/remainderl.m4
+++ b/m4/remainderl.m4
@@ -1,4 +1,4 @@
-# remainderl.m4 serial 8
+# remainderl.m4 serial 9
 dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -100,12 +100,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_remainderl_ieee=yes],
               [gl_cv_func_remainderl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_remainderl_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_remainderl_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_remainderl_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_remainderl_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_remainderl_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_remainderl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/rmdir.m4 b/m4/rmdir.m4
index 37237d2afe..60a4596e6c 100644
--- a/m4/rmdir.m4
+++ b/m4/rmdir.m4
@@ -1,4 +1,4 @@
-# rmdir.m4 serial 14
+# rmdir.m4 serial 15
 dnl Copyright (C) 2002, 2005, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -33,12 +33,12 @@ AC_DEFUN([gl_FUNC_RMDIR],
     ]])],
        [gl_cv_func_rmdir_works=yes], [gl_cv_func_rmdir_works=no],
        [case "$host_os" in
-                  # Guess yes on glibc systems.
-          *-gnu*) gl_cv_func_rmdir_works="guessing yes" ;;
-                  # Guess no on native Windows.
-          mingw*) gl_cv_func_rmdir_works="guessing no" ;;
-                  # If we don't know, assume the worst.
-          *)      gl_cv_func_rmdir_works="guessing no" ;;
+                         # Guess yes on glibc systems.
+          *-gnu* | gnu*) gl_cv_func_rmdir_works="guessing yes" ;;
+                         # Guess no on native Windows.
+          mingw*)        gl_cv_func_rmdir_works="guessing no" ;;
+                         # If we don't know, assume the worst.
+          *)             gl_cv_func_rmdir_works="guessing no" ;;
         esac
        ])
      rm -rf conftest.dir conftest.file])
diff --git a/m4/round.m4 b/m4/round.m4
index d982e592cd..21de3ef177 100644
--- a/m4/round.m4
+++ b/m4/round.m4
@@ -1,4 +1,4 @@
-# round.m4 serial 18
+# round.m4 serial 19
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -113,19 +113,19 @@ int main (int argc, char *argv[])
               [gl_cv_func_round_ieee=yes],
               [gl_cv_func_round_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_round_ieee="guessing yes" ;;
-                         # Guess yes on MSVC, no on mingw.
-                 mingw*) AC_EGREP_CPP([Known], [
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_round_ieee="guessing yes" ;;
+                                # Guess yes on MSVC, no on mingw.
+                 mingw*)        AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                           ],
-                           [gl_cv_func_round_ieee="guessing yes"],
-                           [gl_cv_func_round_ieee="guessing no"])
-                         ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_round_ieee="guessing no" ;;
+                                  ],
+                                  [gl_cv_func_round_ieee="guessing yes"],
+                                  [gl_cv_func_round_ieee="guessing no"])
+                                ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_round_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/roundf.m4 b/m4/roundf.m4
index 0baacc9f51..75645c4be6 100644
--- a/m4/roundf.m4
+++ b/m4/roundf.m4
@@ -1,4 +1,4 @@
-# roundf.m4 serial 19
+# roundf.m4 serial 20
 dnl Copyright (C) 2007-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -113,19 +113,19 @@ int main (int argc, char *argv[])
               [gl_cv_func_roundf_ieee=yes],
               [gl_cv_func_roundf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_roundf_ieee="guessing yes" ;;
-                         # Guess yes on MSVC, no on mingw.
-                 mingw*) AC_EGREP_CPP([Known], [
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_roundf_ieee="guessing yes" ;;
+                                # Guess yes on MSVC, no on mingw.
+                 mingw*)        AC_EGREP_CPP([Known], [
 #ifdef _MSC_VER
  Known
 #endif
-                           ],
-                           [gl_cv_func_roundf_ieee="guessing yes"],
-                           [gl_cv_func_roundf_ieee="guessing no"])
-                         ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_roundf_ieee="guessing no" ;;
+                                  ],
+                                  [gl_cv_func_roundf_ieee="guessing yes"],
+                                  [gl_cv_func_roundf_ieee="guessing no"])
+                                ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_roundf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/roundl.m4 b/m4/roundl.m4
index 47db26b9cc..8b69418a91 100644
--- a/m4/roundl.m4
+++ b/m4/roundl.m4
@@ -1,4 +1,4 @@
-# roundl.m4 serial 16
+# roundl.m4 serial 17
 dnl Copyright (C) 2007, 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -64,12 +64,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_roundl_ieee=yes],
               [gl_cv_func_roundl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_roundl_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_roundl_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_roundl_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_roundl_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_roundl_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_roundl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/select.m4 b/m4/select.m4
index c7844bc8ea..3db0b64464 100644
--- a/m4/select.m4
+++ b/m4/select.m4
@@ -1,4 +1,4 @@
-# select.m4 serial 8
+# select.m4 serial 9
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -74,10 +74,10 @@ changequote([,])dnl
       [gl_cv_func_select_detects_ebadf=no],
           [
            case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_select_detects_ebadf="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_select_detects_ebadf="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_select_detects_ebadf="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_select_detects_ebadf="guessing no" ;;
            esac
           ])
       ])
diff --git a/m4/setenv.m4 b/m4/setenv.m4
index 005aa8cfed..f815b5bcc9 100644
--- a/m4/setenv.m4
+++ b/m4/setenv.m4
@@ -1,4 +1,4 @@
-# setenv.m4 serial 26
+# setenv.m4 serial 27
 dnl Copyright (C) 2001-2004, 2006-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -35,10 +35,10 @@ AC_DEFUN([gl_FUNC_SETENV],
       ]])],
       [gl_cv_func_setenv_works=yes], [gl_cv_func_setenv_works=no],
       [case "$host_os" in
-                 # Guess yes on glibc systems.
-         *-gnu*) gl_cv_func_setenv_works="guessing yes" ;;
-                 # If we don't know, assume the worst.
-         *)      gl_cv_func_setenv_works="guessing no" ;;
+                        # Guess yes on glibc systems.
+         *-gnu* | gnu*) gl_cv_func_setenv_works="guessing yes" ;;
+                        # If we don't know, assume the worst.
+         *)             gl_cv_func_setenv_works="guessing no" ;;
        esac
       ])])
     case "$gl_cv_func_setenv_works" in
diff --git a/m4/signbit.m4 b/m4/signbit.m4
index db60ab724a..a9efe0df54 100644
--- a/m4/signbit.m4
+++ b/m4/signbit.m4
@@ -1,4 +1,4 @@
-# signbit.m4 serial 15
+# signbit.m4 serial 16
 dnl Copyright (C) 2007-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -29,12 +29,12 @@ AC_DEFUN([gl_SIGNBIT],
         [gl_cv_func_signbit=yes],
         [gl_cv_func_signbit=no],
         [case "$host_os" in
-                   # Guess yes on glibc systems.
-           *-gnu*) gl_cv_func_signbit="guessing yes" ;;
-                   # Guess yes on native Windows.
-           mingw*) gl_cv_func_signbit="guessing yes" ;;
-                   # If we don't know, assume the worst.
-           *)      gl_cv_func_signbit="guessing no" ;;
+                          # Guess yes on glibc systems.
+           *-gnu* | gnu*) gl_cv_func_signbit="guessing yes" ;;
+                          # Guess yes on native Windows.
+           mingw*)        gl_cv_func_signbit="guessing yes" ;;
+                          # If we don't know, assume the worst.
+           *)             gl_cv_func_signbit="guessing no" ;;
          esac
         ])
     ])
@@ -60,17 +60,17 @@ AC_DEFUN([gl_SIGNBIT],
         [gl_cv_func_signbit_gcc=yes],
         [gl_cv_func_signbit_gcc=no],
         [case "$host_os" in
-                   # Guess yes on glibc systems.
-           *-gnu*) gl_cv_func_signbit_gcc="guessing yes" ;;
-                   # Guess yes on mingw, no on MSVC.
-           mingw*) if test -n "$GCC"; then
-                     gl_cv_func_signbit_gcc="guessing yes"
-                   else
-                     gl_cv_func_signbit_gcc="guessing no"
-                   fi
-                   ;;
-                   # If we don't know, assume the worst.
-           *)      gl_cv_func_signbit_gcc="guessing no" ;;
+                          # Guess yes on glibc systems.
+           *-gnu* | gnu*) gl_cv_func_signbit_gcc="guessing yes" ;;
+                          # Guess yes on mingw, no on MSVC.
+           mingw*)        if test -n "$GCC"; then
+                            gl_cv_func_signbit_gcc="guessing yes"
+                          else
+                            gl_cv_func_signbit_gcc="guessing no"
+                          fi
+                          ;;
+                          # If we don't know, assume the worst.
+           *)             gl_cv_func_signbit_gcc="guessing no" ;;
          esac
         ])
     ])
diff --git a/m4/sleep.m4 b/m4/sleep.m4
index e2d27be275..ecfd79baf2 100644
--- a/m4/sleep.m4
+++ b/m4/sleep.m4
@@ -1,4 +1,4 @@
-# sleep.m4 serial 8
+# sleep.m4 serial 9
 dnl Copyright (C) 2007-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -46,12 +46,12 @@ handle_alarm (int sig)
     ]])],
       [gl_cv_func_sleep_works=yes], [gl_cv_func_sleep_works=no],
       [case "$host_os" in
-                 # Guess yes on glibc systems.
-         *-gnu*) gl_cv_func_sleep_works="guessing yes" ;;
-                 # Guess no on native Windows.
-         mingw*) gl_cv_func_sleep_works="guessing no" ;;
-                 # If we don't know, assume the worst.
-         *)      gl_cv_func_sleep_works="guessing no" ;;
+                        # Guess yes on glibc systems.
+         *-gnu* | gnu*) gl_cv_func_sleep_works="guessing yes" ;;
+                        # Guess no on native Windows.
+         mingw*)        gl_cv_func_sleep_works="guessing no" ;;
+                        # If we don't know, assume the worst.
+         *)             gl_cv_func_sleep_works="guessing no" ;;
        esac
       ])])
     case "$gl_cv_func_sleep_works" in
diff --git a/m4/stat.m4 b/m4/stat.m4
index 183a70ffe0..ee3dacbc40 100644
--- a/m4/stat.m4
+++ b/m4/stat.m4
@@ -1,4 +1,4 @@
-# serial 13
+# serial 14
 
 # Copyright (C) 2009-2017 Free Software Foundation, Inc.
 #
@@ -43,10 +43,10 @@ AC_DEFUN([gl_FUNC_STAT],
              ]])],
            [gl_cv_func_stat_file_slash=yes], [gl_cv_func_stat_file_slash=no],
            [case "$host_os" in
-                      # Guess yes on glibc systems.
-              *-gnu*) gl_cv_func_stat_file_slash="guessing yes" ;;
-                      # If we don't know, assume the worst.
-              *)      gl_cv_func_stat_file_slash="guessing no" ;;
+                             # Guess yes on glibc systems.
+              *-gnu* | gnu*) gl_cv_func_stat_file_slash="guessing yes" ;;
+                             # If we don't know, assume the worst.
+              *)             gl_cv_func_stat_file_slash="guessing no" ;;
             esac
            ])
          rm -f conftest.tmp conftest.lnk])
diff --git a/m4/strerror.m4 b/m4/strerror.m4
index 279efd60f6..71d577ba13 100644
--- a/m4/strerror.m4
+++ b/m4/strerror.m4
@@ -1,4 +1,4 @@
-# strerror.m4 serial 18
+# strerror.m4 serial 19
 dnl Copyright (C) 2002, 2007-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -24,10 +24,10 @@ AC_DEFUN([gl_FUNC_STRERROR],
         [gl_cv_func_working_strerror=yes],
         [gl_cv_func_working_strerror=no],
         [case "$host_os" in
-                   # Guess yes on glibc systems.
-           *-gnu*) gl_cv_func_working_strerror="guessing yes" ;;
-                   # If we don't know, assume the worst.
-           *)      gl_cv_func_working_strerror="guessing no" ;;
+                          # Guess yes on glibc systems.
+           *-gnu* | gnu*) gl_cv_func_working_strerror="guessing yes" ;;
+                          # If we don't know, assume the worst.
+           *)             gl_cv_func_working_strerror="guessing no" ;;
          esac
         ])
     ])
@@ -78,12 +78,12 @@ AC_DEFUN([gl_FUNC_STRERROR_0],
       [gl_cv_func_strerror_0_works=yes],
       [gl_cv_func_strerror_0_works=no],
       [case "$host_os" in
-                 # Guess yes on glibc systems.
-         *-gnu*) gl_cv_func_strerror_0_works="guessing yes" ;;
-                 # Guess yes on native Windows.
-         mingw*) gl_cv_func_strerror_0_works="guessing yes" ;;
-                 # If we don't know, assume the worst.
-         *)      gl_cv_func_strerror_0_works="guessing no" ;;
+                        # Guess yes on glibc systems.
+         *-gnu* | gnu*) gl_cv_func_strerror_0_works="guessing yes" ;;
+                        # Guess yes on native Windows.
+         mingw*)        gl_cv_func_strerror_0_works="guessing yes" ;;
+                        # If we don't know, assume the worst.
+         *)             gl_cv_func_strerror_0_works="guessing no" ;;
        esac
       ])
   ])
diff --git a/m4/strtok_r.m4 b/m4/strtok_r.m4
index 008bdc472e..161d3415a2 100644
--- a/m4/strtok_r.m4
+++ b/m4/strtok_r.m4
@@ -1,4 +1,4 @@
-# strtok_r.m4 serial 14
+# strtok_r.m4 serial 15
 dnl Copyright (C) 2002-2004, 2006-2007, 2009-2017 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@@ -42,11 +42,11 @@ AC_DEFUN([gl_FUNC_STRTOK_R],
          [gl_cv_func_strtok_r_works=yes],
          [gl_cv_func_strtok_r_works=no],
          [case "$host_os" in
-                    # Guess no on glibc systems.
-            *-gnu*) gl_cv_func_strtok_r_works="guessing no" ;;
-                    # Guess yes on native Windows.
-            mingw*) gl_cv_func_strtok_r_works="guessing yes" ;;
-            *)      gl_cv_func_strtok_r_works="guessing yes" ;;
+                           # Guess no on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_strtok_r_works="guessing no" ;;
+                           # Guess yes on native Windows.
+            mingw*)        gl_cv_func_strtok_r_works="guessing yes" ;;
+            *)             gl_cv_func_strtok_r_works="guessing yes" ;;
           esac
          ])
       ])
diff --git a/m4/symlink.m4 b/m4/symlink.m4
index 220ea1922e..b07121e6fd 100644
--- a/m4/symlink.m4
+++ b/m4/symlink.m4
@@ -1,4 +1,4 @@
-# serial 6
+# serial 7
 # See if we need to provide symlink replacement.
 
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
@@ -36,10 +36,10 @@ AC_DEFUN([gl_FUNC_SYMLINK],
            ]])],
          [gl_cv_func_symlink_works=yes], [gl_cv_func_symlink_works=no],
          [case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_symlink_works="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_symlink_works="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_symlink_works="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_symlink_works="guessing no" ;;
           esac
          ])
       rm -f conftest.f conftest.link conftest.lnk2])
diff --git a/m4/symlinkat.m4 b/m4/symlinkat.m4
index b1a8a99323..9821cf74dd 100644
--- a/m4/symlinkat.m4
+++ b/m4/symlinkat.m4
@@ -1,4 +1,4 @@
-# serial 7
+# serial 8
 # See if we need to provide symlinkat replacement.
 
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
@@ -37,10 +37,10 @@ AC_DEFUN([gl_FUNC_SYMLINKAT],
          [gl_cv_func_symlinkat_works=yes],
          [gl_cv_func_symlinkat_works=no],
          [case "$host_os" in
-                    # Guess yes on glibc systems.
-            *-gnu*) gl_cv_func_symlinkat_works="guessing yes" ;;
-                    # If we don't know, assume the worst.
-            *)      gl_cv_func_symlinkat_works="guessing no" ;;
+                           # Guess yes on glibc systems.
+            *-gnu* | gnu*) gl_cv_func_symlinkat_works="guessing yes" ;;
+                           # If we don't know, assume the worst.
+            *)             gl_cv_func_symlinkat_works="guessing no" ;;
           esac
          ])
       rm -f conftest.f conftest.link conftest.lnk2])
diff --git a/m4/trunc.m4 b/m4/trunc.m4
index f13bb3c7ec..b0810e9088 100644
--- a/m4/trunc.m4
+++ b/m4/trunc.m4
@@ -1,4 +1,4 @@
-# trunc.m4 serial 10
+# trunc.m4 serial 11
 dnl Copyright (C) 2007, 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -70,12 +70,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_trunc_ieee=yes],
               [gl_cv_func_trunc_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_trunc_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_trunc_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_trunc_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_trunc_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_trunc_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_trunc_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/truncf.m4 b/m4/truncf.m4
index fd29ea389b..4a7a2ed51c 100644
--- a/m4/truncf.m4
+++ b/m4/truncf.m4
@@ -1,4 +1,4 @@
-# truncf.m4 serial 10
+# truncf.m4 serial 11
 dnl Copyright (C) 2007, 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -70,12 +70,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_truncf_ieee=yes],
               [gl_cv_func_truncf_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_truncf_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_truncf_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_truncf_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_truncf_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_truncf_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_truncf_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/truncl.m4 b/m4/truncl.m4
index 5fd0411c18..269819aace 100644
--- a/m4/truncl.m4
+++ b/m4/truncl.m4
@@ -1,4 +1,4 @@
-# truncl.m4 serial 12
+# truncl.m4 serial 13
 dnl Copyright (C) 2007-2008, 2010-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -103,12 +103,12 @@ int main (int argc, char *argv[])
               [gl_cv_func_truncl_ieee=yes],
               [gl_cv_func_truncl_ieee=no],
               [case "$host_os" in
-                         # Guess yes on glibc systems.
-                 *-gnu*) gl_cv_func_truncl_ieee="guessing yes" ;;
-                         # Guess yes on native Windows.
-                 mingw*) gl_cv_func_truncl_ieee="guessing yes" ;;
-                         # If we don't know, assume the worst.
-                 *)      gl_cv_func_truncl_ieee="guessing no" ;;
+                                # Guess yes on glibc systems.
+                 *-gnu* | gnu*) gl_cv_func_truncl_ieee="guessing yes" ;;
+                                # Guess yes on native Windows.
+                 mingw*)        gl_cv_func_truncl_ieee="guessing yes" ;;
+                                # If we don't know, assume the worst.
+                 *)             gl_cv_func_truncl_ieee="guessing no" ;;
                esac
               ])
             LIBS="$save_LIBS"
diff --git a/m4/tzset.m4 b/m4/tzset.m4
index 11ceeabed6..dc774b600a 100644
--- a/m4/tzset.m4
+++ b/m4/tzset.m4
@@ -1,4 +1,4 @@
-# serial 10
+# serial 11
 
 # Copyright (C) 2003, 2007, 2009-2017 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -68,12 +68,12 @@ main ()
        [gl_cv_func_tzset_clobber=no],
        [gl_cv_func_tzset_clobber=yes],
        [case "$host_os" in
-                  # Guess all is fine on glibc systems.
-          *-gnu*) gl_cv_func_tzset_clobber="guessing no" ;;
-                  # Guess no on native Windows.
-          mingw*) gl_cv_func_tzset_clobber="guessing no" ;;
-                  # If we don't know, assume the worst.
-          *)      gl_cv_func_tzset_clobber="guessing yes" ;;
+                         # Guess all is fine on glibc systems.
+          *-gnu* | gnu*) gl_cv_func_tzset_clobber="guessing no" ;;
+                         # Guess no on native Windows.
+          mingw*)        gl_cv_func_tzset_clobber="guessing no" ;;
+                         # If we don't know, assume the worst.
+          *)             gl_cv_func_tzset_clobber="guessing yes" ;;
         esac
        ])
     ])
diff --git a/m4/ungetc.m4 b/m4/ungetc.m4
index 9f41c0e1b6..f4b77db7dd 100644
--- a/m4/ungetc.m4
+++ b/m4/ungetc.m4
@@ -1,4 +1,4 @@
-# ungetc.m4 serial 5
+# ungetc.m4 serial 6
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -41,13 +41,12 @@ AC_DEFUN_ONCE([gl_FUNC_UNGETC_WORKS],
            remove ("conftest.tmp");])],
         [gl_cv_func_ungetc_works=yes], [gl_cv_func_ungetc_works=no],
         [case "$host_os" in
-                   # Guess yes on glibc and bionic systems.
-           *-gnu* | *-android*)
-                   gl_cv_func_ungetc_works="guessing yes" ;;
-                   # Guess yes on native Windows.
-           mingw*) gl_cv_func_ungetc_works="guessing yes" ;;
-                   # If we don't know, assume the worst.
-           *)      gl_cv_func_ungetc_works="guessing no" ;;
+                                       # Guess yes on glibc and bionic systems.
+           *-gnu* | gnu* | *-android*) gl_cv_func_ungetc_works="guessing yes" ;;
+                                       # Guess yes on native Windows.
+           mingw*)                     gl_cv_func_ungetc_works="guessing yes" ;;
+                                       # If we don't know, assume the worst.
+           *)                          gl_cv_func_ungetc_works="guessing no" ;;
          esac
         ])
     ])
diff --git a/m4/usleep.m4 b/m4/usleep.m4
index e69ed85b24..dead104220 100644
--- a/m4/usleep.m4
+++ b/m4/usleep.m4
@@ -1,4 +1,4 @@
-# usleep.m4 serial 4
+# usleep.m4 serial 5
 dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -29,12 +29,12 @@ AC_DEFUN([gl_FUNC_USLEEP],
 ]], [[return !!usleep (1000000);]])],
         [gl_cv_func_usleep_works=yes], [gl_cv_func_usleep_works=no],
         [case "$host_os" in
-                   # Guess yes on glibc systems.
-           *-gnu*) gl_cv_func_usleep_works="guessing yes" ;;
-                   # Guess no on native Windows.
-           mingw*) gl_cv_func_usleep_works="guessing no" ;;
-                   # If we don't know, assume the worst.
-           *)      gl_cv_func_usleep_works="guessing no" ;;
+                          # Guess yes on glibc systems.
+           *-gnu* | gnu*) gl_cv_func_usleep_works="guessing yes" ;;
+                          # Guess no on native Windows.
+           mingw*)        gl_cv_func_usleep_works="guessing no" ;;
+                          # If we don't know, assume the worst.
+           *)             gl_cv_func_usleep_works="guessing no" ;;
          esac
         ])])
     case "$gl_cv_func_usleep_works" in
diff --git a/m4/wcwidth.m4 b/m4/wcwidth.m4
index 1243606311..4e9e99b2f4 100644
--- a/m4/wcwidth.m4
+++ b/m4/wcwidth.m4
@@ -1,4 +1,4 @@
-# wcwidth.m4 serial 25
+# wcwidth.m4 serial 26
 dnl Copyright (C) 2006-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -98,9 +98,9 @@ int main ()
           [
 changequote(,)dnl
            case "$host_os" in
-                     # Guess yes on glibc and AIX 7 systems.
-             *-gnu* | aix[7-9]*) gl_cv_func_wcwidth_works="guessing yes";;
-             *)                  gl_cv_func_wcwidth_works="guessing no";;
+                                        # Guess yes on glibc and AIX 7 systems.
+             *-gnu* | gnu* | aix[7-9]*) gl_cv_func_wcwidth_works="guessing yes";;
+             *)                         gl_cv_func_wcwidth_works="guessing no";;
            esac
 changequote([,])dnl
           ])