yuzu: Resolve -Wextra-semi warnings

While we're in the same area, we can ensure GameDir member variables are
always initialized to consistent values.

src/citra_qt/game_list_worker.cpp

@@ -152,7 +152,8 @@ void GameListWorker::run() {
             AddFstEntriesToGameList(game_dir.path.toStdString(), game_dir.deep_scan ? 256 : 0,
                                     game_list_dir);
         }
-    };
+    }
+
     emit Finished(watch_list);
 }