mpc: Update to version 0.34

mpc: Update to version 0.34

- Update from version 0.33 to 0.34
- Combined this patch with update to mpd as mpc depends on mpd
- Changelog
   0.34 (2021/11/30)
	* add commands "albumart", "readpicture"
	* don't print status after error
	* custom status format
	* support grouping "list" results
	* meson: auto-build libmpdclient if not available
	* require libmpdclient 2.16 or newer
	* require MPD 0.21 or newer

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>