For free().

Pulseaudio expects clients to specify their channel-map if the
default (ALSA) map does not route the audio to the expected speakers.

Many Google results suggest dealing with this by re-routing the audio
channels with the appropriate ALSA plugin, but this will then simply
break any clients which expect the default ALSA mapping.

Virtually all media files and codecs, certainly flac, dca, a52, and of
course anything based on Microsoft's WAVEFORMAT_EXTENSIBLE specification,
assume the layout in the table here:
http://en.wikipedia.org/wiki/Surround_sound#Standard_speaker_channels

Fortunately, pulseaudio directly addresses this with a built-in channel
map for WAVE-EX which can be set automatically in the stream sample-spec.

MPD_PATH_MAX_UTF8 is only used by GLib-specific code currently.

Abort if --enable-libmpdclient or --enable-upnp are used with
--disable-database, instead of ignoring the mismatch silently.

Fixes memory leak because ao_plugin_close() never gets called.

Be consistent.

A mutex acts as a memory barrier, and thus "volatile" is not
necessary.

Use the "_format" parameter instead of the (uninitialized) "format"
attribute.

Report unsupported format while opening the filter, not later when the
first conversion takes place.

Fixes assertion failure in destructor by not assigning
{src,dest}_format when an error occurs.

Fixes truncated lines in m3u and cue files (regression by commit
67958f7f).

The file systemd/mpd.service.in is being distributed implicitly, but
systemd/mpd.socket is not and needs to be added to EXTRA_DIST.

Fixes deadlock bug in the "mms" plugin.

Export it from the protected base class.  This fixes a build failure
on Mac OS X.