(get_server_groups): Declare new function.
* security.cc (is_group_member): Simplify.
(get_server_groups): New function.
(get_initgroups_sidlist): Call get_server_groups.
(verify_token): Allow token when supplementary sids are not in
/etc/group but are in the token.
Streamline the code.
* grp.cc (initgroups32): New implementation.
(getgroups32): Handle case where the supplementary groups are set.