CW_ENDENT info types.
* grp.cc (setgrent_filtered): New function, called from cygwin_internal.
(getgrent_filtered): Ditto.
(endgrent_filtered): Ditto.
* passwd.cc (pg_ent::setent): Set state explicitely to from_cache.
(pg_ent::getent): Handle the fact that a DC has no SAM and enumerating
local accounts is equivalent to enumerating domain accounts.
(setpwent_filtered): New function, called from cygwin_internal.
(getpwent_filtered): Ditto.
(endpwent_filtered): Ditto.
* pwdgrp.h (setpwent_filtered): Declare.
(getgrent_filtered): Ditto.
(endgrent_filtered): Ditto.
(setpwent_filtered): Ditto.
(getpwent_filtered): Ditto.
(endpwent_filtered): Ditto.
* include/sys/cygwin.h (cygwin_getinfo_types): Add CW_SETENT, CW_GETENT,
and CW_ENDENT.