[gtkmm] Fix some missing sentinel warnings found by clang++

[Murray Cumming <murrayc src gnome org>]

commit 154a80cdeb2787f4ace126a2d4aefd083b3dbc53
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Mar 15 10:40:08 2012 +0100

    Fix some missing sentinel warnings found by clang++
    
    	* gdk/src/pixbuf.ccg:
    	* gtk/src/cellrenderercombo.ccg: Use (void*)0 instead of NULL.

 ChangeLog                     |    7 +++++++
 gdk/src/pixbuf.ccg            |    2 +-
 gtk/src/cellrenderercombo.ccg |    2 +-
 3 files changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 323a2ed..6b1a9b7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2012-03-15  Murray Cumming  <murrayc murrayc com>
 
+	Fix some missing sentinel warnings found by clang++
+
+	* gdk/src/pixbuf.ccg:
+	* gtk/src/cellrenderercombo.ccg: Use (void*)0 instead of NULL.
+
+2012-03-15  Murray Cumming  <murrayc murrayc com>
+
 	Scale: Add set/get_has_origin() and property.
 
 	* gtk/src/scale.hg: Wrap gtk_scale_set/get_has_origin().
diff --git a/gdk/src/pixbuf.ccg b/gdk/src/pixbuf.ccg
index 6bd6af8..be1cd16 100644
--- a/gdk/src/pixbuf.ccg
+++ b/gdk/src/pixbuf.ccg
@@ -145,7 +145,7 @@ void Pixbuf::save_to_buffer(gchar*& buffer, gsize& buffer_size,
   gdk_pixbuf_save_to_buffer(
       gobj(), &buffer, &buffer_size,
       type.c_str(),
-      &gerror, NULL);
+      &gerror, (void*)0);
 
   if(gerror)
     ::Glib::Error::throw_exception(gerror);
diff --git a/gtk/src/cellrenderercombo.ccg b/gtk/src/cellrenderercombo.ccg
index 4d4c266..cbc7521 100644
--- a/gtk/src/cellrenderercombo.ccg
+++ b/gtk/src/cellrenderercombo.ccg
@@ -29,7 +29,7 @@ static GtkTreeModel* _get_model(GtkCellRendererCombo* renderer)
     return 0;
 
   GtkTreeModel* combo_model = 0;
-  g_object_get(G_OBJECT(renderer), "model", &combo_model, NULL);
+  g_object_get(G_OBJECT(renderer), "model", &combo_model, (void*)0);
   return combo_model;
 }