[krbdev.mit.edu #6041] WIN32 SOCKET != int in gss lib

[Jeffrey Altman via RT]

A WIN32 SOCKET is a HANDLE type and is not equivalent in size to an
'int'.   Windows SOCKET values frequently exceed MAX_INT and become
truncated.  

convert all references to SOCKET and use closesocket() to release the
them instead of the C Runtime Library close() which only applies to file
descriptors.

Proposed patch attached.