Bad flag check

[Francois Gouget]

One of my scripts noticed that the following code does not make sense 
in dlls/winmm/waveform.c:

static DWORD WINMM_NotifyClient(WINMM_CBInfo *info, WORD msg,
       DWORD_PTR param1, DWORD_PTR param2)
{
   if(info->flags & DCB_NULL)
        return MMSYSERR_NOERROR;

That's because DCB_NULL is 0 so this condition is always false. What was 
the intent?