* security.h (class cygpsid): New class.

	* security.h (class cygpsid): New class.
	(class cygsid): Use cygpsid as base. Remove members psid, get_id,
	get_uid, get_gid, string, debug_printf and the == and != operators.
	(cygsidlist::clear_supp): Only do work if setgroups has been called.
	* sec_helper.cc: Define sid_auth NO_COPY.
	(cygpsid::operator==): New operator.
	(cygpsid::get_id): New function.
	(cygpsid::string): New function.
	(cygsid::string): Delete.
	(cygsid::get_id): Delete.
	* pwdgrp.h: Change arguments of internal_getpwsid,
	internal_getgrsid and internal_getgroups to cygpsid.
	* passwd.cc (internal_getpwsid): Change argument from cygsid to cygpsid.
	* grp.cc (internal_getgrsid): Ditto.
	(internal_getgroups): Ditto.