Replace in-line code by call to verify_token().
(setegid): Reverse change from 2002-01-21. Add call to
RevertToSelf and set primary group in impersonation token.
* security.cc (create_token): Store pgrpsid in token security
descriptor, except if it already appears in my_grps.
Use sec_acl() in place of get_dacl().
(verify_token): Create from code in seteuid(), with tighter checks.
(get_dacl) Deleted.
(get_group_sidlist): Add argument to indicate if pgrpsid is already
in the groups.
* security.h: Define verify_token().
* autoload.cc: Load GetKernelObjectSecurity().