Remove inclusion of Xlib headers in Cogl headers

Xlib headers define many trivially named objects which can later cause
name collision problems when only cogl.h header is included in a program
or library. Xlib headers are now only included through including the
standalone header cogl-xlib.h.

https://bugzilla.gnome.org/show_bug.cgi?id=661174

Reviewed-by: Robert Bragg <robert@linux.intel.com>

cogl/cogl-clutter-xlib.h

@@ -0,0 +1,41 @@
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2011 Intel Corporation.
+ *
+ * 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.
+ */
+
+#if !defined(__COGL_XLIB_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
+#error "Only <cogl/cogl-xlib.h> can be included directly."
+#endif
+
+#ifndef __COGL_CLUTTER_XLIB_H__
+#define __COGL_CLUTTER_XLIB_H__
+
+#include <X11/Xutil.h>
+
+G_BEGIN_DECLS
+
+#define cogl_clutter_winsys_xlib_get_visual_info cogl_clutter_winsys_xlib_get_visual_info_CLUTTER
+XVisualInfo *
+cogl_clutter_winsys_xlib_get_visual_info (void);
+
+G_END_DECLS
+
+#endif /* __COGL_CLUTTER_XLIB_H__ */