DRASCULA: Fix axe visibility flag when entering room 31

The visible[1] flag in room 31 (i.e. for the axe) is now reset according
to flags[13] (which indicate if we picked up the axe already or not).

This fixes bug #7118 Drascula: Axe item can be picked up infinite
times

engines/drascula/objects.cpp

@@ -272,6 +272,8 @@ void DrasculaEngine::updateVisible() {
 			visible[2] = 0;
 		if (_roomNumber == 26 && flags[12] == 1)
 			visible[1] = 0;
+		if (_roomNumber == 31 && flags[13] == 1)
+			visible[1] = 0;
 		if (_roomNumber == 35 && flags[14] == 1)
 			visible[2] = 0;
 		if (_roomNumber == 35 && flags[17] == 1)