PulseAudio causes an assert if being relocked inside a callback on the worker
thread, where aluHandleDisconnect is called. We can assume it's already locked
there, so just make sure the device is locked before being calling it.
This allows us to properly update the ALCdevice and its resources with the new
parameters before starting playback, instead of expecting the mixer to block
and wait after it has begun.
This also lets us avoid holding the device lock while resetting and starting
the device, which helps prevent lock inversion on some backends (ie, one thread
locking A then B, and another thread locking B then A), ultimately allowing
certain backends to asynchronously update the ALCdevice without risk of lockup.
Capture still has issues here, however.
