[glib] Add a forgotten include guard

[Matthias Clasen <matthiasc src gnome org>]

commit e927df7b7ab089f5e7de452a509130c06e13e4f9
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Mar 24 23:00:15 2012 -0400

    Add a forgotten include guard
    
    gbytes.h was missing the single-include guard.

 glib/gbytes.h |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/glib/gbytes.h b/glib/gbytes.h
index a120e21..de3c8f8 100644
--- a/glib/gbytes.h
+++ b/glib/gbytes.h
@@ -21,6 +21,10 @@
  *         Stef Walter <stefw collabora co uk>
  */
 
+#if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
+#error "Only <glib.h> can be included directly."
+#endif
+
 #ifndef __G_BYTES_H__
 #define __G_BYTES_H__