fix boost macros on non-GNU systems

Both boost_system and boost_filesystem macros rely on the GNU `tac`
tool and sed behaviour which isn't compatible with POSIX systems, like
Mac OS X. This updates both files with upstream fixes from
autoconf-archive; one patch is already in the repository, the other
has been submitted.

m4/ax_boost_filesystem.m4

@@ -81,14 +81,14 @@ AC_DEFUN([AX_BOOST_FILESYSTEM],
 			AC_DEFINE(HAVE_BOOST_FILESYSTEM,,[define if the Boost::Filesystem library is available])
             BOOSTLIBDIR=`echo $BOOST_LDFLAGS | sed -e 's/@<:@^\/@:>@*//'`
             if test "x$ax_boost_user_filesystem_lib" = "x"; then
-                for libextension in `ls $BOOSTLIBDIR/libboost_filesystem*.so* $BOOSTLIBDIR/libboost_filesystem*.dylib* $BOOSTLIBDIR/libboost_filesystem*.a* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^lib\(boost_filesystem.*\)\.\(dylib\|a\|so\).*$;\1;' | tac` ; do
+                for libextension in `ls -r $BOOSTLIBDIR/libboost_filesystem* 2>/dev/null | sed 's,.*/lib,,' | sed 's,\..*,,'` ; do
                      ax_lib=${libextension}
 				    AC_CHECK_LIB($ax_lib, exit,
                                  [BOOST_FILESYSTEM_LIB="-l$ax_lib"; AC_SUBST(BOOST_FILESYSTEM_LIB) link_filesystem="yes"; break],
                                  [link_filesystem="no"])
 				done
                 if test "x$link_filesystem" != "xyes"; then
-                for libextension in `ls $BOOSTLIBDIR/boost_filesystem*.dll* $BOOSTLIBDIR/boost_filesystem*.a* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^\(boost_filesystem.*\)\.\(dll\|a\).*$;\1;' | tac` ; do
+                for libextension in `ls -r $BOOSTLIBDIR/boost_filesystem* 2>/dev/null | sed 's,.*/,,' | sed -e 's,\..*,,'` ; do
                      ax_lib=${libextension}
 				    AC_CHECK_LIB($ax_lib, exit,
                                  [BOOST_FILESYSTEM_LIB="-l$ax_lib"; AC_SUBST(BOOST_FILESYSTEM_LIB) link_filesystem="yes"; break],

m4/ax_boost_system.m4

@@ -83,14 +83,14 @@ AC_DEFUN([AX_BOOST_SYSTEM],
 
 			LDFLAGS_SAVE=$LDFLAGS
             if test "x$ax_boost_user_system_lib" = "x"; then
-                for libextension in `ls $BOOSTLIBDIR/libboost_system*.a* $BOOSTLIBDIR/libboost_system*.so* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^lib\(boost_system.*\)\.\(so\|a\).*$;\1;' | tac` ; do
+                for libextension in `ls -r $BOOSTLIBDIR/libboost_system* 2>/dev/null | sed 's,.*/lib,,' | sed 's,\..*,,'` ; do
                      ax_lib=${libextension}
 				    AC_CHECK_LIB($ax_lib, exit,
                                  [BOOST_SYSTEM_LIB="-l$ax_lib"; AC_SUBST(BOOST_SYSTEM_LIB) link_system="yes"; break],
                                  [link_system="no"])
 				done
                 if test "x$link_system" != "xyes"; then
-                for libextension in `ls $BOOSTLIBDIR/boost_system*.{dll,a}* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^\(boost_system.*\)\.\(dll\|a\).*$;\1;' | tac` ; do
+                for libextension in `ls -r $BOOSTLIBDIR/boost_system* 2>/dev/null | sed 's,.*/,,' | sed -e 's,\..*,,'` ; do
                      ax_lib=${libextension}
 				    AC_CHECK_LIB($ax_lib, exit,
                                  [BOOST_SYSTEM_LIB="-l$ax_lib"; AC_SUBST(BOOST_SYSTEM_LIB) link_system="yes"; break],