recentchooserdefault: Clean up load_id when we have nothing left to do

Returning FALSE from a GSourceFunc will implicitly remove it, so we need
to do this in order to make the new g_source_remove happy.

gtk/gtkrecentchooserdefault.c

@@ -762,6 +762,7 @@ load_recent_items (gpointer user_data)
       chooser_set_model (impl);
 
       retval = FALSE;
+      impl->priv->load_id = 0;
     }
   else
     {