mciwave: need to serialize record and play

[Joerg-Cyril.Hoehle at t-systems.com]

Eric,

I've not yet tested your patches but I thought to additionaly use STATUS_NOT_READY
as an intermittent marker for work in progress, so other threads know something
is going on and don't pull the carpet under the feet. What do you think?
E.g. play; play from 0; play from 1000; play from 0; seek to 0; should be handled correctly
(including NOTIFY ABORTED with play notify; play from 0 notify; play ... notify; seek notify).

This may or may not eventually be completed by a critical section in record+play. I don't know yet.

Eric, I can stop working on mciwave for the moment to avoid git conflicts
and go check another D3D issue. Do you plan to work on
- the record+play as well as
- the 333ms issues?

After the new notification system gets in play, I'll change mcimidi and mcicda.
Because these are the interesting drivers, mciwave has just the advantage that
it does not depend on other broken code (Timidity).

BTW, I found the ADPCM and µ-law samples I use on http://en.wikipedia.org/wiki/Dct_(File_Format)

Regards,
 Jörg Höhle.