Avoid a possible deadlock when stopping playback

[Dmitry Timoshkov]

Hello,

looks like it's a good idea to do the same when signalling hStopEvent.

Changelog:
    Dmitry Timoshkov <dmitry at codeweavers.com>
    Avoid a possible deadlock when stopping playback.

--- cvs/hq/wine/dlls/winmm/mciavi/mciavi.c	2004-03-16 18:37:03.000000000 +0800
+++ wine/dlls/winmm/mciavi/mciavi.c	2004-03-16 19:38:42.000000000 +0800
@@ -606,7 +606,9 @@ static	DWORD	MCIAVI_mciStop(UINT wDevID,
     switch (wma->dwStatus) {
     case MCI_MODE_PLAY:
     case MCI_MODE_RECORD:
+        LeaveCriticalSection(&wma->cs);
         SetEvent(wma->hStopEvent);
+        EnterCriticalSection(&wma->cs);
         /* fall through */
     case MCI_MODE_PAUSE:
 	/* Since our wave notification callback takes the lock,