[gtk+] Fix a compilation warning: use NULL instead ""

[Javier Jardón <jjardon src gnome org>]

commit c43a3acac3d56d7fb67c996450d3d1ca9f7668e7
Author: Javier Jardón <jjardon gnome org>
Date:   Wed Oct 21 19:41:50 2009 +0200

    Fix a compilation warning: use NULL instead ""

 gtk/gtkselection.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkselection.c b/gtk/gtkselection.c
index 7195b86..f6187b2 100644
--- a/gtk/gtkselection.c
+++ b/gtk/gtkselection.c
@@ -3067,7 +3067,7 @@ gtk_selection_default_handler (GtkWidget	*widget,
     {
       gtk_selection_data_set (data,
 			      gdk_atom_intern_static_string ("NULL"),
-			      32, "", 0);
+			      32, NULL, 0);
     }
   else
     {