aclocal.m4: add support for w64-ming32 builds

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@67050 15284696-431f-4ddb-bdfa-cd5b030d7da7

aclocal.m4

@@ -501,7 +501,7 @@ AC_DEFUN([SC_CONFIG_CFLAGS], [
             LDFLAGS="-Wl,--export-dynamic"
 	    LD_LIBRARY_PATH_VAR="PATH"
 	    ;;
-        *-pc-mingw32 | *-pc-msys)
+        *-pc-mingw32 | *-w64-mingw32 | *-pc-msys)
             SHLIB_SUFFIX=".dll"
             SHLIB_LD="${CC} -shared"
             LDFLAGS="-Wl,--export-dynamic,--enable-runtime-pseudo-reloc"