[Zope-Coders] Zope HEAD doesn't compile on Windows

[Matt Behrens]

> ...which uses grp.h, which doesn't appear to exist.
> 
> If whoever broke this could fix it, I'd be very grateful. Mr Behrens,
I believe that's you
> ;-)

initgroups is a useless concept on Windows, so all that's needed is to
somehow conditionally remove it from Setup20 if not on a UNIXy platform.

I don't know the first thing about non-distutils building on Windows, so
any help here would be appreciated.