winmm: Have MCI drivers handle notification for MCI_OPEN.

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

Hi,

>http://testbot.winehq.org/JobDetails.pl?Key=2193
>While running your changed tests on Windows, I think I found new failures.

These are among the known set of 7 flaky tests (in vmware only?), e.g. see
http://test.winehq.org/data/f00d44f0f63a66b9157ff7334f6b54c8b079c1ee/98_wtb-w98se/winmm:mci.html

while on the next day, everything succeeds:
http://test.winehq.org/data/658209b57164da96919500468114a6a7eb0bf7b5/98_wtb-w98se/winmm:mci.html

Regards,
 Jörg Höhle