Eliminate the fallback strndup() and strnlen() implementations.

Cast to integer after multiplying with 1000.  Allows sub-second
seeking.

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.