Fixed missing inversion in bit manipulation.

diff --git a/dlls/winmm/winmm.c b/dlls/winmm/winmm.c
index e9dbf97..66a6a4f 100644
--- a/dlls/winmm/winmm.c
+++ b/dlls/winmm/winmm.c
@@ -1983,7 +1983,7 @@
 	lpMidiHdr = (LPMIDIHDR)msg->lParam;
 	lpMidiHdr->lpNext = 0;
 	lpMidiHdr->dwFlags |= MHDR_INQUEUE;
-	lpMidiHdr->dwFlags &= MHDR_DONE;
+	lpMidiHdr->dwFlags &= ~MHDR_DONE;
 	lpMidiHdr->dwOffset = 0;
 
 	break;