[Patch] Using Windows groups for SSPI authentication

I have some code that I've been using that supports adding and
authenticating Windows groups via the pg_ident file. This is useful for
sysadmins as it lets them control database access outside the database
using Windows groups. It has a new
indicator (+), that signifies the identifier is a Windows group, as in the
following example:

# MAPNAME SYSTEM-USERNAME PG-USERNAME
"Users" "+User group" postgres

A new function was added to test if a user token is in the windows group:

/*
* Check if the user (sspiToken) is a member of the specified group
*/
static BOOL
sspi_user_is_in_group(HANDLE sspiToken, LPCTSTR groupName)

Attached is the patch.

thanks,
Russell Foster