tree view: Avoid a crash with rubberbanding

When a treeview is destroyed while rubberbanding is going
on, we crash because the rb tree is nuked before we want
to access it to stop the rubberbanding. To avoid this crash
end the rubberbanding early in destroy().

See
https://bugzilla.redhat.com/show_bug.cgi?id=1173904

gtk/gtktreeview.c

@@ -2120,6 +2120,7 @@ gtk_tree_view_destroy (GtkWidget *widget)
   GList *list;
 
   gtk_tree_view_stop_editing (tree_view, TRUE);
+  gtk_tree_view_stop_rubber_band (tree_view);
 
   if (tree_view->priv->columns != NULL)
     {