Deprecate GLIB_GNU_GETTEXT macro, use upstream gettext instead

https://bugzilla.gnome.org/show_bug.cgi?id=624186

m4macros/glib-gettext.m4

@@ -313,7 +313,7 @@ msgstr ""
 # on various variables needed by the Makefile.in.in installed by 
 # glib-gettextize.
 dnl
-glib_DEFUN([GLIB_GNU_GETTEXT],
+AU_DEFUN([GLIB_GNU_GETTEXT],
   [AC_REQUIRE([AC_PROG_CC])dnl
    
    GLIB_LC_MESSAGES
@@ -383,7 +383,8 @@ glib_DEFUN([GLIB_GNU_GETTEXT],
    rm -f po/POTFILES
    sed -e "/^#/d" -e "/^\$/d" -e "s,.*,	$posrcprefix& \\\\," -e "\$s/\(.*\) \\\\/\1/" \
 	< $srcdir/po/POTFILES.in > po/POTFILES
-  ])
+  ],
+  [[$0: This macro is deprecated. You should use upstream gettext instead.]])
 
 # AM_GLIB_DEFINE_LOCALEDIR(VARIABLE)
 # -------------------------------