Update to 2.10:

libmpdclient 2.10 (2015/02/23)
* support abstract sockets with "@" prefix
* support tag "MUSICBRAINZ_RELEASETRACKID"
* add TCP keepalive internal and external APIs
* support MPD protocol 0.19
  - status: support sample formats "float" and "dsd"
  - song: report duration with milliseconds precision
  - search: support constraint "modified-since"
* support MPD protocol 0.20
  - the "window" parameter for commands "find"/"search"

(wiz)