incorrect VOMS AC verification (#89948)

[sustr4]

This is a copy of original issue https://savannah.cern.ch/bugs/index.php?89948 by Zdenek Salvet

1. When multiple VOMS server certificates with the same public
   key are present in vomdir, expired one can be chosen and
   AC ignored even though valid one is present too.
2. VOMS server certificates are not checked against CRLs