[glib] gsource: Make GSource->source_funcs const

[Ryan Lortie <ryanl src gnome org>]

commit ed8ec635eb37099d36581b4b66dd24148940ebfa
Author: Ryan Lortie <desrt desrt ca>
Date:   Mon Oct 29 16:31:46 2012 +0100

    gsource: Make GSource->source_funcs const
    
    This is the vtable pointer for the source which is usually held in
    static storage.  For our internal sources it points at a vtable which
    the user should really never be modifying.
    
    Mark it const.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=686853

 glib/gmain.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/glib/gmain.h b/glib/gmain.h
index 90bc035..90ff11b 100644
--- a/glib/gmain.h
+++ b/glib/gmain.h
@@ -156,7 +156,7 @@ struct _GSource
   gpointer callback_data;
   GSourceCallbackFuncs *callback_funcs;
 
-  GSourceFuncs *source_funcs;
+  const GSourceFuncs *source_funcs;
   guint ref_count;
 
   GMainContext *context;