Header files not present on Windows

[Patrik Stridvall]

> Patrik Stridvall <ps at leissner.se> writes:
> 
> > Hmm. I'm note sure I like making unistd.h 
> > an optional header but then few part of
> > Wine should include it anyway so perhaps
> > it doesn't matter.
> 
> The question is whether you can build without it. If the needed
> definitions are provided by other includes then it's fine to make it
> optional; but if the code doesn't compile without it then there's no
> point in having a check.

Yes and in many cases it did work without unistd.h, but maybe that
is because it really wasn't needed at all.

In some case it might have worked because some of the functions in
unistd.h is defined else where in Windows and in some case we might
get it to work by including needed files.

Of course in such cases we probably should fix Wine and
include that other header exclusively instead of unistd.h.

Anyway, I just experimented a little trying to get Wine to compile
under Windows. I'm not really sure exacly what to do.

Eventually I guess that the non-core DLL:s never should call any
non Windows functions at all and the core DLL:s are not really useful
to compile and run under Windows anyway.