gdk: Put stub gdkx.h into gdk/ dir

This is so we can include gdk/gdkx.h from inside GTK code.

gdk/Makefile.am

@@ -107,7 +107,8 @@ gdk_private_headers = 				\
 	gdkinternals.h				\
 	gdkintl.h				\
 	gdkkeysprivate.h			\
-	gdkvisualprivate.h
+	gdkvisualprivate.h			\
+	gdkx.h
 
 gdk_c_sources = 				\
 	gdk.c					\

gdk/gdkx.h

@@ -0,0 +1,33 @@
+/* GDK - The GIMP Drawing Kit
+ * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/*
+ * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
+ * file for a list of people on the GTK+ Team.  See the ChangeLog
+ * files for a list of changes.  These files are distributed with
+ * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
+ */
+
+/* This is a cludge to be able to include gdk/gdkx.h from inside the
+ * GTK source tree.
+ * Also, this hopefully serves as a warning to new backends to put
+ * their header into the backend dir from the start.
+ */
+
+#include <gdk/x11/gdkx.h>