[gnome-control-center] keyboard: Don't leak a dialog

[Bastien Nocera <hadess src gnome org>]

commit f444c7b28c1e4ca52f37630e17381842c3616f47
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Sep 17 14:49:10 2013 +0200

    keyboard: Don't leak a dialog
    
    https://bugzilla.gnome.org/show_bug.cgi?id=708286

 panels/keyboard/keyboard-shortcuts.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/panels/keyboard/keyboard-shortcuts.c b/panels/keyboard/keyboard-shortcuts.c
index 5b0c815..ddaf588 100644
--- a/panels/keyboard/keyboard-shortcuts.c
+++ b/panels/keyboard/keyboard-shortcuts.c
@@ -1926,5 +1926,7 @@ keyboard_shortcuts_dispose (CcPanel *panel)
 
   g_clear_object (&binding_settings);
 
+  g_clear_pointer (&custom_shortcut_dialog, gtk_widget_destroy);
+
   cc_keyboard_option_clear_all ();
 }