Squashed commit of the following:

commit 233cbc2a39b348eb66f70e7806f5fe2ef45db6a8
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Mar 6 11:37:05 2020 +0200

    Update ChangeLog files with Jannick's changes.

commit 3a6297d5a1e900f8de0ddc6dda5b08770483e318
Author: Arnold D. Robbins <arnold@skeeve.com>
Date:   Fri Feb 21 13:10:40 2020 +0200

    MSYS2 build changes.

1 files changed, 92 insertions, 6 deletions

diff --git a/configure b/configure
index e41ee237..fa674929 100755
--- a/configure
+++ b/configure
@@ -3339,6 +3339,98 @@ IFS=$ac_save_IFS
 case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac
 
 
+ax_tt_header_is_printed=:
+case x$ax_disable_triplet_transform/`uname` in #(
+  x/MSYS*) :
+
+if test x$ac_cv_build != x; then
+  ax_tt_var=`echo $ac_cv_build | sed 's|-msys$|-cygwin|'`
+  if test x$ax_tt_var = x; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: sed script: build triplet conversion \`$ac_cv_build' with sed script \`s|-msys$|-cygwin|'failed." >&5
+$as_echo "$as_me: sed script: build triplet conversion \`$ac_cv_build' with sed script \`s|-msys$|-cygwin|'failed." >&6;}
+  elif test x$ax_tt_var != x`$SHELL "$ac_aux_dir/config.sub" $ax_tt_var`; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: \`config.sub' test: build triplet conversion of \`$ac_cv_build' produced invalid triplet \`$ax_tt_var'." >&5
+$as_echo "$as_me: \`config.sub' test: build triplet conversion of \`$ac_cv_build' produced invalid triplet \`$ax_tt_var'." >&6;}
+  elif test x$ax_tt_var != x$ac_cv_build; then
+          if test x$ax_tt_header_is_printed != xyes; then
+        ax_tt_header_is_printed=yes
+        { $as_echo "$as_me:${as_lineno-$LINENO}: Triplet conversion on MSYS platform:" >&5
+$as_echo "$as_me: Triplet conversion on MSYS platform:" >&6;}
+      fi
+    gawk_cv_build_orig=$ac_cv_build
+    ac_cv_build=$ax_tt_var
+    { $as_echo "$as_me:${as_lineno-$LINENO}: build: replacing $gawk_cv_build_orig -> $ac_cv_build" >&5
+$as_echo "$as_me: build: replacing $gawk_cv_build_orig -> $ac_cv_build" >&6;}
+    ax_tt_var=
+    case $ac_cv_build in
+*-*-*) ;;
+*) as_fn_error $? "invalid value of canonical build" "$LINENO" 5;;
+esac
+build=$ac_cv_build
+ac_save_IFS=$IFS; IFS='-'
+set x $ac_cv_build
+shift
+build_cpu=$1
+build_vendor=$2
+shift; shift
+# Remember, the first character of IFS is used to create $*,
+# except with old shells:
+build_os=$*
+IFS=$ac_save_IFS
+case $build_os in *\ *) build_os=`echo "$build_os" | sed 's/ /-/g'`;; esac
+
+  fi
+  ax_tt_var=
+fi
+
+
+if test x$ac_cv_host != x; then
+  ax_tt_var=`echo $ac_cv_host | sed 's|-msys$|-cygwin|'`
+  if test x$ax_tt_var = x; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: sed script: host triplet conversion \`$ac_cv_host' with sed script \`s|-msys$|-cygwin|'failed." >&5
+$as_echo "$as_me: sed script: host triplet conversion \`$ac_cv_host' with sed script \`s|-msys$|-cygwin|'failed." >&6;}
+  elif test x$ax_tt_var != x`$SHELL "$ac_aux_dir/config.sub" $ax_tt_var`; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: \`config.sub' test: host triplet conversion of \`$ac_cv_host' produced invalid triplet \`$ax_tt_var'." >&5
+$as_echo "$as_me: \`config.sub' test: host triplet conversion of \`$ac_cv_host' produced invalid triplet \`$ax_tt_var'." >&6;}
+  elif test x$ax_tt_var != x$ac_cv_host; then
+          if test x$ax_tt_header_is_printed != xyes; then
+        ax_tt_header_is_printed=yes
+        { $as_echo "$as_me:${as_lineno-$LINENO}: Triplet conversion on MSYS platform:" >&5
+$as_echo "$as_me: Triplet conversion on MSYS platform:" >&6;}
+      fi
+    gawk_cv_host_orig=$ac_cv_host
+    ac_cv_host=$ax_tt_var
+    { $as_echo "$as_me:${as_lineno-$LINENO}: host: replacing $gawk_cv_host_orig -> $ac_cv_host" >&5
+$as_echo "$as_me: host: replacing $gawk_cv_host_orig -> $ac_cv_host" >&6;}
+    ax_tt_var=
+    case $ac_cv_host in
+*-*-*) ;;
+*) as_fn_error $? "invalid value of canonical host" "$LINENO" 5;;
+esac
+host=$ac_cv_host
+ac_save_IFS=$IFS; IFS='-'
+set x $ac_cv_host
+shift
+host_cpu=$1
+host_vendor=$2
+shift; shift
+# Remember, the first character of IFS is used to create $*,
+# except with old shells:
+host_os=$*
+IFS=$ac_save_IFS
+case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac
+
+  fi
+  ax_tt_var=
+fi
+
+
+ ;; #(
+  *) :
+     ;;
+esac
+
+
 DEPDIR="${am__leading_dot}deps"
 
 ac_config_commands="$ac_config_commands depfiles"
@@ -11057,17 +11149,11 @@ ac_config_headers="$ac_config_headers config.h:configh.in"
 
 
 
-if test "x$EXEEXT" = x.exe; then :
-  GAWKLIBEXT=dll
-else
-
 case $acl_shlibext in
 dylib)	GAWKLIBEXT=so ;;	# MacOS uses .dylib for shared libraries, but libtool uses .so for modules
 *) GAWKLIBEXT=$acl_shlibext ;;
 esac
 
-fi
-
 
 ac_config_files="$ac_config_files Makefile support/Makefile awklib/Makefile doc/Makefile extras/Makefile po/Makefile.in test/Makefile"