Ticket 47885 - deref plugin should not return references with noc access rights
    
    Bug Description:  deref shows derefernced entries for which th client doesn't
                      have access as dn and empty attribute list
    
    Fix Description:   if client has no accesss to the derferernced entry then
                       omit it from the list in the deref control
                       In general, if no entries are returned don't send an empty control
    
    https://fedorahosted.org/389/ticket/47885
    
    Reviewed by: noriko, thanks