[krbdev.mit.edu #6041] WIN32 SOCKET != int in gss and rpc libs

[Ken Raeburn via RT]

closesocket returns an int as close does.  If we're intentionally  
ignoring the return values, please keep the (void) casts, at least for  
now.

Why do you need to define INVALID_SOCKET in svc_udp.c?

Ken