* security.cc (get_unix_group_sidlist): Create.

	* security.cc (get_unix_group_sidlist): Create.
	(get_supplementary_group_sidlist): Evolve into get_unix_group_sidlist.
	(get_user_local_groups): Add check for duplicates.
	(get_user_primary_group): Suppress.
	(get_group_sidlist): Silently ignore PDC unavailability.
	Call get_unix_group_sidlist() before get_user_local_groups().
	Remove call to get_supplementary_group_sidlist(). Never call
	get_user_primary_group() as the passwd group is always included.
	Add well_known_authenticated_users_sid in only one statement.