It is pointless to let WasapiOutputThread wait for the
CheckException() call.

If an exception has been caught, the method cannot continue playback,
therefore it doesn't make sense to have the "catch" block inside the
"while" block (and not break the loop after catching an exception).

The current Drain() implementation does what Cancel() should do; it
does not wait for completion, but instead discards the buffer.

None of the current FormatHResultError() callers need the format string.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1102

Stop early, don't try more formats if it is clear that we have no
chance.

Fixes assertion failure in the Thread destructor.

Fixes crash due to std::stoul() throwing std::invalid_argument.

Reduce header dependencies.

Fixes linker failure on test/run_output.exe

Shorter.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

* Use PcmExport for 24bit packed output