Remove customlevelstatsloaded from Game

This boolean is assigned, and it is checked... but it's never assigned
to true, thus making it useless. I also checked 2.2 source and the same
thing happens there; to prevent any confusion, I'm removing this.

desktop_version/src/Game.h

@@ -416,7 +416,6 @@ public:
     void updatecustomlevelstats(std::string clevel, int cscore);
 
     std::vector<CustomLevelStat> customlevelstats;
-    bool customlevelstatsloaded;
 
 
     std::vector<SDL_GameControllerButton> controllerButton_map;