[gtk] Menu: Don't leak priv->motion_controller

[Daniel Boles <dboles src gnome org>]

commit f8ecd488cdc6f115d343888bffc52b7037edbb8a
Author: Daniel Boles <dboles src gmail com>
Date:   Sat Mar 24 21:57:42 2018 +0000

    Menu: Don't leak priv->motion_controller

 gtk/gtkmenu.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gtk/gtkmenu.c b/gtk/gtkmenu.c
index 22f86a1e51..946bbb1444 100644
--- a/gtk/gtkmenu.c
+++ b/gtk/gtkmenu.c
@@ -1232,6 +1232,7 @@ gtk_menu_finalize (GObject *object)
   gtk_widget_unparent (priv->bottom_arrow_widget);
   g_clear_object (&priv->click_gesture);
   g_clear_object (&priv->scroll_controller);
+  g_clear_object (&priv->motion_controller);
 
   G_OBJECT_CLASS (gtk_menu_parent_class)->finalize (object);
 }