[gtk+] gtk/gtkbuiltinicon.c: Fix build

[Chun-wei Fan <fanchunwei src gnome org>]

commit 7a054328430cd7ee7fa63b11e7e7d8bb4754776c
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Tue Dec 22 16:33:32 2015 +0800

    gtk/gtkbuiltinicon.c: Fix build
    
    The gtk_builtin_icon_get_default_size_property returns a const char *,
    in a way such that some compilers insist that something that is of a
    pointer value be returned, so fix that by replacing 0 with NULL.

 gtk/gtkbuiltinicon.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkbuiltinicon.c b/gtk/gtkbuiltinicon.c
index 8a57a61..a6974e6 100644
--- a/gtk/gtkbuiltinicon.c
+++ b/gtk/gtkbuiltinicon.c
@@ -271,7 +271,7 @@ gtk_builtin_icon_get_default_size_property (GtkBuiltinIcon *icon)
 {
   GtkBuiltinIconPrivate *priv;
 
-  g_return_val_if_fail (GTK_IS_BUILTIN_ICON (icon), GTK_CSS_IMAGE_BUILTIN_NONE);
+  g_return_val_if_fail (GTK_IS_BUILTIN_ICON (icon), NULL);
 
   priv = gtk_builtin_icon_get_instance_private (icon);