Support cross-compilation to musl libc.

Reported by Necktwi Ozfguah <necktwi@ferryfair.com>.

* m4/calloc.m4 (_AC_FUNC_CALLOC_IF): Add cross-compilation guesses for
musl libc.
* m4/canonicalize.m4 (gl_FUNC_REALPATH_WORKS): Likewise.
* m4/cbrtl.m4 (gl_FUNC_CBRTL): Likewise.
* m4/ceil.m4 (gl_FUNC_CEIL): Likewise.
* m4/ceilf.m4 (gl_FUNC_CEILF): Likewise.
* m4/ceill.m4 (gl_FUNC_CEILL): Likewise.
* m4/chown.m4 (gl_FUNC_CHOWN): Likewise.
* m4/d-ino.m4 (gl_CHECK_TYPE_STRUCT_DIRENT_D_INO): Likewise.
* m4/exp2l.m4 (gl_FUNC_EXP2L): Likewise.
* m4/expl.m4 (gl_FUNC_EXPL): Likewise.
* m4/expm1.m4 (gl_FUNC_EXPM1): Likewise.
* m4/expm1l.m4 (gl_FUNC_EXPM1L): Likewise.
* m4/fdopendir.m4 (gl_FUNC_FDOPENDIR): Likewise.
* m4/floor.m4 (gl_FUNC_FLOOR): Likewise.
* m4/floorf.m4 (gl_FUNC_FLOORF): Likewise.
* m4/fmod.m4 (gl_FUNC_FMOD): Likewise.
* m4/fmodf.m4 (gl_FUNC_FMODF): Likewise.
* m4/fmodl.m4 (gl_FUNC_FMODL): Likewise.
* m4/fnmatch.m4 (gl_FUNC_FNMATCH_POSIX): Likewise.
* m4/fpurge.m4 (gl_FUNC_FPURGE): Likewise.
* m4/getcwd.m4 (gl_FUNC_GETCWD_NULL): Likewise.
* m4/getcwd-abort-bug.m4 (gl_FUNC_GETCWD_ABORT_BUG): Likewise.
* m4/getdelim.m4 (gl_FUNC_GETDELIM): Likewise.
* m4/getgroups.m4 (AC_FUNC_GETGROUPS, gl_FUNC_GETGROUPS): Likewise.
* m4/getline.m4 (gl_FUNC_GETLINE): Likewise.
* m4/gettimeofday.m4 (gl_FUNC_GETTIMEOFDAY_CLOBBER): Likewise.
* m4/hypot.m4 (gl_FUNC_HYPOT): Likewise.
* m4/hypotf.m4 (gl_FUNC_HYPOTF): Likewise.
* m4/hypotl.m4 (gl_FUNC_HYPOTL): Likewise.
* m4/iconv_open-utf.m4 (gl_FUNC_ICONV_OPEN_UTF_SUPPORT): Likewise.
* m4/link-follow.m4 (gl_FUNC_LINK_FOLLOWS_SYMLINK): Likewise.
* m4/log.m4 (gl_FUNC_LOG): Likewise.
* m4/logf.m4 (gl_FUNC_LOGF): Likewise.
* m4/logl.m4 (gl_FUNC_LOGL_WORKS): Likewise.
* m4/log10.m4 (gl_FUNC_LOG10): Likewise.
* m4/log10f.m4 (gl_FUNC_LOG10F): Likewise.
* m4/log10l.m4 (gl_FUNC_LOG10L): Likewise.
* m4/log1p.m4 (gl_FUNC_LOG1P): Likewise.
* m4/log1pf.m4 (gl_FUNC_LOG1PF): Likewise.
* m4/log1pl.m4 (gl_FUNC_LOG1PL): Likewise.
* m4/log2.m4 (gl_FUNC_LOG2): Likewise.
* m4/log2f.m4 (gl_FUNC_LOG2F): Likewise.
* m4/malloc.m4 (_AC_FUNC_MALLOC_IF): Likewise.
* m4/mkdir.m4 (gl_FUNC_MKDIR): Likewise.
* m4/mkstemp.m4 (gl_FUNC_MKSTEMP): Likewise.
* m4/modf.m4 (gl_FUNC_MODF): Likewise.
* m4/modff.m4 (gl_FUNC_MODFF): Likewise.
* m4/modfl.m4 (gl_FUNC_MODFL): Likewise.
* m4/perror.m4 (gl_FUNC_PERROR): Likewise.
* m4/printf.m4 (gl_PRINTF_SIZES_C99, gl_PRINTF_INFINITE,
gl_PRINTF_INFINITE_LONG_DOUBLE, gl_PRINTF_DIRECTIVE_A,
gl_PRINTF_DIRECTIVE_F, gl_PRINTF_FLAG_ZERO, gl_SNPRINTF_TRUNCATION_C99,
gl_SNPRINTF_RETVAL_C99, gl_SNPRINTF_DIRECTIVE_N,
gl_VSNPRINTF_ZEROSIZE_C99): Likewise.
* m4/ptsname.m4 (gl_FUNC_PTSNAME): Likewise.
* m4/putenv.m4 (gl_FUNC_PUTENV): Likewise.
* m4/realloc.m4 (_AC_FUNC_REALLOC_IF): Likewise.
* m4/remainder.m4 (gl_FUNC_REMAINDER): Likewise.
* m4/remainderf.m4 (gl_FUNC_REMAINDERF): Likewise.
* m4/remainderl.m4 (gl_FUNC_REMAINDERL): Likewise.
* m4/rintl.m4 (gl_FUNC_RINTL): Likewise.
* m4/round.m4 (gl_FUNC_ROUND): Likewise.
* m4/roundf.m4 (gl_FUNC_ROUNDF): Likewise.
* m4/roundl.m4 (gl_FUNC_ROUNDL): Likewise.
* m4/setenv.m4 (gl_FUNC_SETENV): Likewise.
* m4/signbit.m4 (gl_SIGNBIT): Likewise.
* m4/sleep.m4 (gl_FUNC_SLEEP): Likewise.
* m4/stpncpy.m4 (gl_FUNC_STPNCPY): Likewise.
* m4/strerror.m4 (gl_FUNC_STRERROR, gl_FUNC_STRERROR_0): Likewise.
* m4/strtod.m4 (gl_FUNC_STRTOD): Likewise.
* m4/strtold.m4 (gl_FUNC_STRTOLD): Likewise.
* m4/trunc.m4 (gl_FUNC_TRUNC): Likewise.
* m4/truncf.m4 (gl_FUNC_TRUNCF): Likewise.
* m4/truncl.m4 (gl_FUNC_TRUNCL): Likewise.
* m4/tzset.m4 (gl_FUNC_TZSET_CLOBBER): Likewise.
* m4/ungetc.m4 (gl_FUNC_UNGETC_WORKS): Likewise.
* m4/usleep.m4 (gl_FUNC_USLEEP): Likewise.
* m4/utimes.m4 (gl_FUNC_UTIMES): Likewise.
* m4/wcwidth.m4 (gl_FUNC_WCWIDTH): Likewise.

1 files changed, 2 insertions, 2 deletions

diff --git a/m4/malloc.m4 b/m4/malloc.m4
index b9b8d4b46e..c469c4508d 100644
--- a/m4/malloc.m4
+++ b/m4/malloc.m4
@@ -1,4 +1,4 @@
-# malloc.m4 serial 18
+# malloc.m4 serial 19
 dnl Copyright (C) 2007, 2009-2019 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* | gnu* | freebsd* | netbsd* | openbsd* \
+          *-gnu* | gnu* | *-musl* | freebsd* | netbsd* | openbsd* \
           | hpux* | solaris* | cygwin* | mingw*)
             ac_cv_func_malloc_0_nonnull="guessing yes" ;;
           # If we don't know, assume the worst.