sanlock: add lockspace checks
    
    When comparing lockspaces, do a full compare of name, and
    host_id path/offset/id when possible.  This prevent adding
    two lockspaces with the same name but different host_id info.
    
    (Of course two lockspaces with the same never should never
    be created in the first place.  We can't fully protect
    against that, so it's a user error, but we can reject it
    when we see it.)