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/yuzu/game_list_worker.cpp

@@ -374,7 +374,7 @@ void GameListWorker::run() {
             ScanFileSystem(ScanTarget::PopulateGameList, game_dir.path.toStdString(),
                            game_dir.deep_scan ? 256 : 0, game_list_dir);
         }
-    };
+    }
 
     emit Finished(watch_list);
 }