LILLIPUT: Fixes rendering by blitting mainSurface to screen

Before displayMousePointer() that calls display16x16IndexedBuf() did the
blit and I forgot to add it when removing the custom cursor handling in
38cd5b2ac3.

engines/lilliput/lilliput.cpp

@@ -257,6 +257,7 @@ void LilliputEngine::update() {
 			CursorMan.popCursor();
 		}
 
+		_system->copyRectToScreen((byte *)_mainSurface->getPixels(), 320, 0, 0, 320, 200);
 		_system->updateScreen();
 	}
 }