Remove handling Android back button from the engine

src/GameEngine.c

@@ -758,13 +758,6 @@ void handle_events() {
     switch (GameEngine.event.type) {
     case SDL_QUIT:
       GameEngine.running = false;
-      break;
-    case SDL_KEYUP:
-      if (GameEngine.event.key.keysym.sym == SDLK_AC_BACK) {
-        // Handle Android's back button
-        GameEngine.running = false;
-      }
-
       break;
     }