[gtk+] menu: Don't leak check menu items

[Matthias Clasen <matthiasc src gnome org>]

commit 3a947fa318e50db950609d319523e495995b98f6
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Nov 23 14:48:17 2016 -0500

    menu: Don't leak check menu items
    
    Pointed out in
    https://bugzilla.gnome.org/show_bug.cgi?id=774686

 gtk/gtkmenu.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkmenu.c b/gtk/gtkmenu.c
index 7839098..514dd67 100644
--- a/gtk/gtkmenu.c
+++ b/gtk/gtkmenu.c
@@ -3056,6 +3056,8 @@ static void gtk_menu_measure (GtkWidget      *widget,
           max_toggle_size = indicator_width;
 
           gtk_widget_destroy (menu_item);
+          g_object_ref_sink (menu_item);
+          g_object_unref (menu_item);
         }
 
       min_width += 2 * max_toggle_size + max_accel_width;