cogl: include <cogl/cogl-xlib.h> for xlib specific symbols

Since Xlib.h is such a terrible citizen when it comes to symbol
namespacing it's not desirable to include Xlib.h if it is not absolutely
required. Cogl now has a standalone cogl-xlib.h that should be included
whenever any xlib specific symbols are required.

This patch updates clutter to include <cogl/cogl-xlib.h> wherever
clutter needs to use xlib specific cogl apis.

Acked-by: Emmanuele Bassi <ebassi@linux.intel.com>

clutter/cogl/clutter-backend-cogl.c

@@ -55,6 +55,8 @@
 #include "clutter-cex100.h"
 #endif
 
+#include <cogl/cogl-xlib.h>
+
 static ClutterBackendCogl *backend_singleton = NULL;
 
 static gchar *clutter_vblank = NULL;

clutter/x11/clutter-backend-x11.c

@@ -59,6 +59,7 @@
 #endif
 
 #include <cogl/cogl.h>
+#include <cogl/cogl-xlib.h>
 
 #include "clutter-backend.h"
 #include "clutter-debug.h"