musicpd: update to 0.22.1.

ver 0.22.1 (2020/10/17)
* decoder
  - opus: apply the OpusHead output gain even if there is no EBU R128 tag
  - opus: fix track/album ReplayGain fallback
* output
  - alsa: don't deadlock when the ALSA driver is buggy
  - jack, pulse: reduce the delay when stopping or pausing playback
* playlist
  - cue: fix two crash bugs
* state_file: fix the state_file_interval setting

(wiz)