Actually use search results from the model

We didn't connect to the signals, so we never picked up
any search results from the model engine. Good thing, since
it was returning the wrong thing.

gtk/gtksearchengine.c

@@ -481,6 +481,7 @@ _gtk_search_engine_set_model (GtkSearchEngine    *engine,
   if (model)
     {
       engine->priv->model = _gtk_search_engine_model_new (model);
+      connect_engine_signals (engine->priv->model, engine);
       if (engine->priv->query)
         _gtk_search_engine_set_query (engine->priv->model, engine->priv->query);
     }