When a program becomes unavailable, it should unregister itself with the rpcbind program on the same machine.
The parameters and results have meanings identical to those of RPCBPROC_SET. The mapping of the (prog, vers, netid) tuple with uaddr is deleted.
If netid is NULL, all mappings specified by the ordered set (prog, vers, *) and the corresponding universal addresses are deleted. Only the owner of the service or the super-user is allowed to unset a service.