Don't initialize game.gametimer in the header file

That's a C++ thing apparently.

desktop_version/src/Game.cpp

@@ -365,6 +365,7 @@ void Game::init(void)
     skipfakeload = false;
 
     ghostsenabled = false;
+    gametimer = 0;
 
     cliplaytest = false;
     playx = 0;

desktop_version/src/Game.h

@@ -392,7 +392,7 @@ public:
     bool shouldreturntoeditor;
 #endif
 
-    int gametimer = 0;
+    int gametimer;
 };
 
 extern Game game;