Add gss_userok and gss_pname_to_uid
Resurrect gss_userok and gss_pname_to_uid in the mechglue. Add krb5
mech implementations using krb5_kuserok and krb5_aname_to_localname,
as well as mechanism-independent implementations based on name
attributes.
From r24710, r24715, r24717, r24731, r24732, r24733, r24734, r24735,
r24747, r24816, and r24819 in users/lhoward/moonshot-mechglue-fixes,
with minor edits.
ticket: 6891
git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@24836
dc483132-0cff-0310-8789-
dd5450dbe970