[Settings] Move "setting not found" log to excessive level
[C++] C++ fixes for compiling with g++ on the Pi.
[FPD] Fix race condition in FPD output thread start/stop

There was a race condition where new data could come in after
the FPD output thread was told to stop.  In FPD_StopOutputThread(),
we were waiting checking to make sure there was no more data waiting.
This race caused us to wait until the next sequence ended meaning we
would skip sequences during playback because the main channel output thread
could not be started again.  Instead we now check to see if the FPD
output thread has stopped or wait up to 110ms max to make sure that
we will allow the main channel output thread to continue.