Various debug conditional compilation cleanup (#2915)

* Global: Define DEBUG as 0 if not already defined

* Clean up DEBUG-guarded code

src/d/d_com_inf_game.cpp

@@ -1783,7 +1783,7 @@ void dComIfGs_gameStart() {
     dComIfGp_setNextStage(name, point, roomNo, -1, 0.0f, 0, 1, 0, 0, 0, 0);
 }
 
-#ifdef DEBUG
+#if DEBUG
 void dComIfG_playerStatusD() {
     dComIfGs_setDataNum(0);
     dComIfGs_setMaxLife(50);