http://bugs.winehq.org/show_bug.cgi?id=23866
--- Comment #6 from Dmitry Timoshkov dmitry@codeweavers.com 2010-08-16 00:15:50 --- (In reply to comment #5)
+250 cdecl _MCIWndCreate(word word long str) MCIWndCreate16
Why do you think that 16-bit MCIWndCreate is supposed to be cdecl? If that's really the case you need to add CDECL to the API implementation.
I've found an old copy of 16-bit VFW SDK, and MCIWndCreate is really cdecl there.