[Bug 38241] Open General crashes when exiting.

https://bugs.winehq.org/show_bug.cgi?id=38241

--- Comment #7 from Sagawa  ---
(In reply to Andrew Eikum from comment #6)
> Some tests indicate this is wrong. MCI seems to reject commands from the
> thread that didn't open them with MCIERR_INVALID_DEVICE_NAME. See attached
> tests, run here:
>
> https://testbot.winehq.org/JobDetails.pl?Key=22738

Yes, MCI seems to reject commands across threads on Windows NT, but not true on
Windows 9x. I'm afraid introduce some incompatibilities for them.
However, my approach introduces some issues as seen in Bug 40179. Now, I agree
with reverting 46d5973 and introduce thread checks. Thanks.