[gtk+] Silence another compiler warning

[Matthias Clasen <matthiasc src gnome org>]

commit 6f829d445063eeb54097957706a33a516d4604aa
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Mar 22 15:20:43 2015 -0400

    Silence another compiler warning
    
    Again, our habit of comparing enum values against -1.

 gtk/gtkrender.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkrender.c b/gtk/gtkrender.c
index bb1f437..20c014d 100644
--- a/gtk/gtkrender.c
+++ b/gtk/gtkrender.c
@@ -1189,7 +1189,7 @@ gtk_render_icon_pixbuf (GtkStyleContext     *context,
                         GtkIconSize          size)
 {
   g_return_val_if_fail (GTK_IS_STYLE_CONTEXT (context), NULL);
-  g_return_val_if_fail (size > GTK_ICON_SIZE_INVALID || size == -1, NULL);
+  g_return_val_if_fail (size > GTK_ICON_SIZE_INVALID || size == (GtkIconSize)-1, NULL);
   g_return_val_if_fail (source != NULL, NULL);
 
   return gtk_do_render_icon_pixbuf (context, source, size);