TETRIS: Fix restart

tetris/functions.cpp

@@ -118,6 +118,8 @@ void quitGame() {
 }
 
 void resetGame() {
+    std::lock_guard< std::mutex > guard( g_render_mutex );
+    std::lock_guard< std::mutex > guard2( g_movement_mutex );
     g_cur_object.reset();
     g_checked_line = true;
     g_next_object.reset();