* security.cc: Swap out several functions.
* sec_acl.cc: New file. Move Sun compatibel ACL functions from
`security.cc' to here.
* sec_helper.cc: New file. Move security helper functions from
`security.cc' to here.
* security.h: Changed to accomodate the above changes.
* grp.cc: Replace `group_in_memory_p' by `group_state'.
Eliminate group_sem throughout.
(enum grp_state): New enumeration type.
(read_etc_group): Make race safe.
* security.cc: Eliminate group_sem throughout.
