SCUMM: Prevent expiration of music while it's playing

This brings isSoundInUse() and isSoundRunning() closer to each other,
while still maintaining the documented differences. It seems to fix a
problem I had where the "follow the shopkeeper" music in the Mac version
of Monkey Island 1 expired when reaching the island overhead map,
causing the music to be be replaced with the regular overhead map theme.

engines/scumm/sound.cpp

@@ -1013,17 +1013,19 @@ bool Sound::isSoundInUse(int sound) const {
 	if (sound == _currentCDSound)
 		return pollCD() != 0;
 
+	if (_mixer->isSoundIDActive(sound))
+		return true;
+
 	if (isSoundInQueue(sound))
 		return true;
 
-	if (!_vm->_res->isResourceLoaded(rtSound, sound))
+	if (sound > _vm->_numSounds || !_vm->_res->isResourceLoaded(rtSound, sound))
 		return false;
 
 	if (_vm->_imuse)
 		return _vm->_imuse->get_sound_active(sound);
-
-	if (_mixer->isSoundIDActive(sound))
-		return 1;
+	else if (_vm->_musicEngine)
+		return _vm->_musicEngine->getSoundStatus(sound);
 
 	return false;
 }