getport: RPC_PROGNOTREGISTERED is a permanent error

rpcbind returns RPC_PROGNOTREGISTERED if it knows for certain that an
RPC program is not supported for a given transport.  This is a
permanent and authoritative error, so the library's rpcbind query API
should never retry the query -- it will only get the same answer.

A similar change was submitted for libtirpc.  Unlike rpcb_getaddr(3t),
mount.nfs's rpcbind client only retries once (with RPCB3PROC_GETADDR),
but an extra TCP socket in this case would leave another port in
TIME_WAIT.  It's infrequent enough, but might as well get rid of it.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>