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

[Bastien Nocera <hadess src gnome org>]

commit 3b485b6df27e5f6d6f9352b2216c9c494d11bc32
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Sep 17 18:04:57 2013 +0200

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

 panels/user-accounts/um-account-dialog.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/panels/user-accounts/um-account-dialog.c b/panels/user-accounts/um-account-dialog.c
index cdf0288..8feaca0 100644
--- a/panels/user-accounts/um-account-dialog.c
+++ b/panels/user-accounts/um-account-dialog.c
@@ -1581,6 +1581,8 @@ um_account_dialog_dispose (GObject *obj)
                 self->enterprise_domain_timeout_id = 0;
         }
 
+        g_clear_pointer (&self->join_dialog, gtk_widget_destroy);
+
         G_OBJECT_CLASS (um_account_dialog_parent_class)->dispose (obj);
 }