Revision 420515

- Fix high CPU usage while recording and playing at the same time,
  report better sio_onmove deltas [1]
- Fix issues with underruns when the system is under high load
- Fix sio_getcap [1]
- Fallback to /dev/dsp (hw.snd.default_unit) in sndiod and libsndio when no
  other device is specified [1]
- rc.d script now configures a monitoring sub-device (a fake recording stream
  with a mix of all playback streams) by default [1]
- Use OPSYS for better portability

PR:		212007 [1]
Submitted by:	Tobias Kortkamp (maintainer) [1]