No caller needs this.  Fixes use-after-free after returning from
Client::OnTimeout().

Save the state file 2 minutes after the last change.  This reduces the
disruptions by an idle MPD, and MPD can be paged out permanently until
it is used.

Only relevant for old ffmpeg versions.

Fixes valgrind warning.

Eliminates one IDLE_PLAYER call in playlist_control, and add two new
ones to player_thread.  Fixes Mantis bug 3636.

Check audio_format_defined().

AVFrame must be allocated with avcodec_alloc_frame().

AVFrame must be allocated with avcodec_alloc_frame().

Use the GMainLoop specific function to wake up the main loop.  This is
simpler and comes with very little overhead.

Don't bother checking for the parameter mask.  This doesn't matter.
The only thing that matters is if a wake-up is already pending.

Less overhead than fetch_and() for what we do.

Fixes segmentation fault.

If END is omitted, mpd should use the highest possible value instead of raising an error.
This partially reverts 52e9cab1

Workaround for driver bug observed on the Raspberry Pi, see code
comment for details.

Fixes nullptr dereference in std::string::operator=().  Also fixes a
memory leak by using config_get_block_string() instead of
config_dup_block_string().

Fixes assertion failure.

Would require gcc 4.7, and MPD attempts to be compatible with gcc 4.6.

When all outputs fail, MPD automatically pauses playback, but did not
emit the IDLE_PLAYER event.  Thus, clients were not woken up.  (Mantis
3665)