The registerrpc routine performs the following tasks for a
    server:
    o  Creates a UDP server handle. See the svcudp_create routine for
       restrictions.
    o  Calls the svc_register routine to register the program with
       the Portmapper.
    o  Adds prognum, versnum, and procnum to an internal list of
       registered procedures. When the server receives a request, it
       uses this list to determine which routine to call.

    A server should call registerrpc for every procedure it
    implements, except for the NULL procedure. If a request arrives
    for program prognum, version versnum, and procedure procnum,
    progname is called with a pointer to its parameters.