sanlock: print better names in direct read -s
    
    sanlock direct read -s LOCKSPACE
    was printing "write_id, write_generation, write_timestamp"
    field names which are relevant only for paxos leases.
    Print "extra1, extra2, extra3" as the field names when
    reading a lockspace.
    
    Signed-off-by: David Teigland <teigland@redhat.com>