Remove useless variable game.coins

It kept getting set to 0 and getting incremented sometimes, but without
it ever actually getting checked, it's a useless variable.

desktop_version/src/Game.h

@@ -247,7 +247,7 @@ public:
 
     int deathseq, lifeseq;
 
-    int coins, trinkets(), crewmates();
+    int trinkets(), crewmates();
     int savepoint, teleport, teleportxpos;
     int edteleportent;
     bool completestop;