[gtk+/native-layout] Fix compilation warning: cast to GCompareFunc

[Tristan Van Berkom <tvb src gnome org>]

commit c59386ba1d09b9c61930ffd7c877048f5608bd7d
Author: Javier Jardón <jjardon gnome org>
Date:   Thu Feb 11 00:56:48 2010 +0100

    Fix compilation warning: cast to GCompareFunc

 gtk/gtkscale.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkscale.c b/gtk/gtkscale.c
index 4c3f478..a69e053 100644
--- a/gtk/gtkscale.c
+++ b/gtk/gtkscale.c
@@ -1426,7 +1426,8 @@ gtk_scale_add_mark (GtkScale        *scale,
   mark->markup = g_strdup (markup);
   mark->position = position;
  
-  priv->marks = g_slist_insert_sorted (priv->marks, mark, compare_marks);
+  priv->marks = g_slist_insert_sorted (priv->marks, mark,
+                                       (GCompareFunc) compare_marks);
 
   n = g_slist_length (priv->marks);
   values = g_new (gdouble, n);