AUDIO: Add pure virtual MidiDriver::isOpen() method

This in turn enables modifying MidiDriver_MPU401::close() to allow
it to be called on a midi driver that has not yet been opened.

The specific issue that triggered me to make these changes was a
crash-upon-quit in HUGO, caused by it instantiating a midi driver,
then encountering an error (missing hugo.dat) *before* having
opened the new midi driver; the general cleanup code then tries
to close the (not yet opened) midi driver -> kaboom

Also fixed some engines which were leaking MidiDriver instances.

1 files changed, 1 insertions, 0 deletions

diff --git a/engines/sci/sound/drivers/mididriver.h b/engines/sci/sound/drivers/mididriver.h
index f745d62716..5cecebd325 100644
--- a/engines/sci/sound/drivers/mididriver.h
+++ b/engines/sci/sound/drivers/mididriver.h
@@ -89,6 +89,7 @@ public:
 		return open(resMan);
 	}
 	virtual int open(ResourceManager *resMan) { return _driver->open(); }
+	bool isOpen() const { return _driver->isOpen(); }
 	virtual void close() { _driver->close(); }
 	virtual void send(uint32 b) { _driver->send(b); }
 	uint32 getBaseTempo() { return _driver->getBaseTempo(); }