[gtk+] Add missing X11/Xlib.h include required for X11/extensions/sync.h

[Robert Ancell <rancell src gnome org>]

commit 6188ea608f14fbfbb14fe7e4ad6dabc65d34c9de
Author: Robert Ancell <robert ancell canonical com>
Date:   Wed Dec 8 18:44:20 2010 +1100

    Add missing X11/Xlib.h include required for X11/extensions/sync.h

 gdk/x11/gdkwindow-x11.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.h b/gdk/x11/gdkwindow-x11.h
index fd63e8b..0c02b67 100644
--- a/gdk/x11/gdkwindow-x11.h
+++ b/gdk/x11/gdkwindow-x11.h
@@ -35,6 +35,7 @@
 #endif
 
 #ifdef HAVE_XSYNC
+#include <X11/Xlib.h>
 #include <X11/extensions/sync.h>
 #endif