ipa-kdb: skip verification of PAC full checksum
    
    MIT Kerberos KDC code will do verification of the PAC full checksum
    buffers, we don't need to process them. This change only applies to
    newer MIT Kerberos version which have this buffer type defined, hence
    using #ifdef to protect the use of the define.
    
    This should have no functional difference.
    
    Related: https://pagure.io/freeipa/issue/9371
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Julien Rische <jrische@redhat.com>