[gtk+] Add missing include

[Matthias Clasen <matthiasc src gnome org>]

commit 05abea6c4fb7bf1db0ca72c65b255af975208278
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Dec 8 11:35:06 2010 -0500

    Add missing include
    
    See bug 636732

 gdk/x11/gdkwindow-x11.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.h b/gdk/x11/gdkwindow-x11.h
index 0c02b67..85d892b 100644
--- a/gdk/x11/gdkwindow-x11.h
+++ b/gdk/x11/gdkwindow-x11.h
@@ -30,6 +30,8 @@
 #include "gdk/x11/gdkprivate-x11.h"
 #include "gdk/gdkwindowimpl.h"
 
+#include <X11/Xlib.h>
+
 #ifdef HAVE_XDAMAGE
 #include <X11/extensions/Xdamage.h>
 #endif