Log Message:
musicpd: Update to 0.21.21

ver 0.21.21 (2020/03/19)
* configuration
  - fix bug in "metadata_to_use" setting
* playlist
  - asx, xspf: fix corrupt tags in the presence of XML entities
* archive
  - iso9660: skip empty file names to work around libcdio bug
* decoder
  - gme: ignore empty tags
* output
  - solaris: port to NetBSD
* raise default "max_connections" value to 100