Index: aclocal/ax_check_compile_flag.m4
==================================================================
--- aclocal/ax_check_compile_flag.m4
+++ aclocal/ax_check_compile_flag.m4
@@ -1,7 +1,7 @@
 # ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+#  https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
 # ===========================================================================
 #
 # SYNOPSIS
 #
 #   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
@@ -27,37 +27,16 @@
 # LICENSE
 #
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   This program is free software: you can redistribute it and/or modify it
-#   under the terms of the GNU General Public License as published by the
-#   Free Software Foundation, either version 3 of the License, or (at your
-#   option) any later version.
-#
-#   This program is distributed in the hope that it will be useful, but
-#   WITHOUT ANY WARRANTY; without even the implied warranty of
-#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
-#   Public License for more details.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <http://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
-
-#serial 4
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 6
 
 AC_DEFUN([AX_CHECK_COMPILE_FLAG],
 [AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
 AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
 AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [

Index: aclocal/shobj.m4
==================================================================
--- aclocal/shobj.m4
+++ aclocal/shobj.m4
@@ -112,22 +112,24 @@
 		])
 
 		LDFLAGS="$OLD_LDFLAGS"
 		unset OLD_LDFLAGS
 
-		ADDLDFLAGS=""
-		for opt in $LDFLAGS $LIBS; do
-			if echo "$opt" | grep '^-L' >/dev/null; then
-				rpathdir="`echo "$opt" | sed 's@^-L *@@'`"
-				ADDLDFLAGS="$ADDLDFLAGS $rsk_cv_link_set_rpath -Wl,$rpathdir"
-			fi
-		done
-		unset opt
-
-		LDFLAGS="$LDFLAGS $ADDLDFLAGS"
-
-		unset ADDLDFLAGS
+		if test -n "$rsk_cv_link_set_rpath"; then
+			ADDLDFLAGS=""
+			for opt in $LDFLAGS $LIBS; do
+				if echo "$opt" | grep '^-L' >/dev/null; then
+					rpathdir="`echo "$opt" | sed 's@^-L *@@'`"
+					ADDLDFLAGS="$ADDLDFLAGS $rsk_cv_link_set_rpath -Wl,$rpathdir"
+				fi
+			done
+			unset opt
+
+			LDFLAGS="$LDFLAGS $ADDLDFLAGS"
+
+			unset ADDLDFLAGS
+		fi
 	fi
 ])
 
 AC_DEFUN([DC_CHK_OS_INFO], [
 	AC_CANONICAL_HOST
@@ -162,11 +164,10 @@
 						;;
 				esac
 				;;
 			mingw32|mingw32msvc*)
 				SHOBJEXT="dll"
-				AREXT='lib'
 				CFLAGS="$CFLAGS -mms-bitfields"
 				CPPFLAGS="$CPPFLAGS -mms-bitfields"
 				SHOBJCPPFLAGS="-DPIC"
 				SHOBJLDFLAGS='-shared -Wl,--dll -Wl,--enable-auto-image-base -Wl,--output-def,$[@].def,--out-implib,$[@].a'
 				;;