* include/cygwin/version.h: Bump API minor version.
* cygheap.h (class cygheap_user): Add member groups.
* security.h (class cygsidlist): Add members type and maxcount,
methods position, addfromgr, alloc_sids and free_sids and
operator+= (const PSID psid). Modify contains () to call
position () and optimize add () to use maxcount.
(class user_groups): Create.
Update declarations of verify_token and create_token.
* security.cc (cygsidlist::alloc_sids): New.
(cygsidlist::free_sids): New.
(get_token_group_sidlist): Create from get_group_sidlist.
(get_initgroups_sidlist): Create from get_group_sidlist.
(get_group_sidlist): Suppress.
(get_setgroups_sidlist): Create.
(verify_token): Modify arguments. Add setgroups case.
(create_token): Modify arguments. Call get_initgroups_sidlist and
get_setgroups_sidlist as needed. Set SE_GROUP_LOGON_ID from auth_pos
outside of the loop. Rename the various group sid lists consistently.
* syscalls.cc (seteuid32): Modify to use cygheap->user.groups.
(setegid32): Call cygheap->user.groups.update_pgrp.
* grp.cc (setgroups): Create.
(setgroups32): Create.
* uinfo.cc (internal_getlogin): Initialize and update user.groups.pgsid.
* cygwin.din: Add setgroups and setgroups32.