Allows running the unit tests on Linux.

Got lost in commit 0f56ddb8

This avoids underruns at the start of playback.

This was missing in commit 8a243e6e

If draining was not requested, generate silence instead if there is no
data in the ring buffer.

The problem is that pw_stream_flush() appears to disable the stream
permanently, even though there is no state_changed callback - the
stream state remains at PW_STREAM_STATE_STREAMING, but the stream is
defunct.  I have no idea why and I havn't found any documentation
about it.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1219

This was missing in commit 4d1ce702

release v0.22.10

This replaces 967af603 with a more
effective workaround.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/822

snd_mixer_handle_events() has already been called by
DispatchSockets().  This way, we can also skip the exception handler.

The "install_dev" target runs ranlib during installation, and this
can break the Android build.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1019

Prepending "../" to absolute URIs would break them.

If UpdateStreamTag() gets called while an initial seek is pending, the
result will never be submitted to a MusicChunk.  By avoiding the
UpdateStreamTag() call in that case (by moving UpdateStreamTag() to
after the PrepareInitialSeek() check), the song_tag is preserved until
UpdateStreamTag() is called again from SubmitData().

This fixes missing tags in the "httpd" output.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1137