dsound: Don't copy the notify object on duplicate.

dlls/dsound/buffer.c

@@ -1213,6 +1213,7 @@ HRESULT IDirectSoundBufferImpl_Duplicate(
     dsb->ref = 0;
     dsb->state = STATE_STOPPED;
     dsb->buf_mixpos = dsb->sec_mixpos = 0;
+    dsb->notify = NULL;
     dsb->device = device;
     dsb->ds3db = NULL;
     dsb->iks = NULL; /* FIXME? */

dlls/dsound/tests/dsound.c

@@ -1185,7 +1185,6 @@ static HRESULT test_duplicate(LPGUID lpGuid)
                                 event,WAIT_OBJECT_0+1);
 
                     ref=IDirectSoundNotify_Release(dup_notify);
-                    todo_wine
                     ok(ref==0,"IDirectSoundNotify_Release() has %d references, "
                        "should have 0\n",ref);
                 }