libOggFLAC has been deprecated for 5 years now, and we havn't been
testing it for a long time.  Let's delete it.

Conflicts:
	configure.ac
	src/output_control.c

.. and a minor tweak for libFLAC+libogg detection.

Eliminate an unnecessary source of deadlocks.

The pkg-config file was added by the Debian package maintainers, and
unfortunately, the rest of the world doesn't have it.

Add M4 function MPD_AUTO_PKG_LIB for pkg-config with AC_CHECK_LIB
fallback.

Don't abort the configure script when avahi could not be
auto-detected.  It previously did, because there was no custom "fail"
action for PKG_CHECK_MODULES.

Don't add those to MPD_CFLAGS / MPD_LIBS.

Better name, better documentation.

The output thread could hang indefinitely after finishing CANCEL,
because it could have missed the signal while the output was not
unlocked in ao_command_finished().

This patch removes the wait() call after CANCEL, and adds the flag
"allow_play" instead.  While this flag is set, playback is skipped.
With this flag, there will not be any excess wait() call after the
pipe has been cleared.

This patch fixes a bug that causes mpd to discontinue playback after
seeking, due to the race condition described above.

Fixes assertion failure when a stream callback is invoked too late
after a format change.

Merge common code.

Eliminate duplicate code.

The value of this is not used, the code is commented out - let's get
rid of it.

Make the code portable.

Doesn't exist on mingw32.

Fix compilation on mingw32.

usleep() is not portable.

When the caller isn't interested in the values.

Check if the time difference is negative.  That would have caused
sleeping forever.

Fix yet another memory leak.

.. and fix a few memory leaks.

.. and destruct the output object properly in test/run_output.

.. and fix a double free bug.

This fixes a bug that caused all values to be an empty string.

Just move a pointer, don't call strlen() in every iteration.

Eliminate the redundant local variable "i".

This must persist iterations.

Restore some of the original file structure from from raop_play.