Game list: propely hide on toggling window mode

Properly hides the game list upon toggling from external
window mode to single window mode. Previously, both the game
list and the render window would have been shown at the same
time upon toggling.

src/citra_qt/main.cpp

@@ -458,6 +458,7 @@ void GMainWindow::ToggleWindowMode() {
         if (emulation_running) {
             render_window->setVisible(true);
             render_window->setFocus();
+            game_list->hide();
         }
 
     } else {