Handle the removal of KRB5_KDB_FLAG_ALIAS_OK
    
    In ac8865a22138ab0c657208c41be8fd6bc7968148 (between 1.17 and 1.18),
    krb5 removed this flag, and always accepts aliases.
    
    Related-to: https://pagure.io/freeipa/issue/7879
    Signed-off-by: Robbie Harwood <rharwood@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>