alsa:

alsa:
- fixed callback thread to exit normally if error condition was satisfied during stream processing (OnExit wasn't called), it was possible cause of crash if error happened inside the thread
- modified processing thread to timeout during poll() within around 2 seconds instead of 64 milliseconds, this will help to fix problems on systems with low processing power and possible CPU overloading, like portable ARM devices
- timeout of poll() will not cause stream to stop but will cause Alsa stream restart, poll timeout will now set 'xrun' event to 1