Every physical link faces outside, up or down

The filter accepts what does not arrive on a link the machine names as
outward, and the host named only links carrying a default route. An
unplugged wired port was left unfiltered for whenever it was plugged in
(novox/hq issue 197). A link backed by a physical device is now named
whether or not it is up.

cmd/mesh-host/main.go

@@ -1421,7 +1421,7 @@ func applyAndKeep(ctx context.Context, opts options, raw []byte, signed *store.D
 	// (novox/hq ADR 0140). Reported whatever the node's mode: a converged node's filter needs it,
 	// and an adopted one becomes converged without a further round trip. A machine that cannot read
 	// its own routing table says nothing rather than guessing, and is sent no filter.
-	if links, err := outward.Links(""); err != nil {
+	if links, err := outward.Links("", ""); err != nil {
 		fmt.Fprintf(os.Stderr, "mesh-host: applied, and could not read which links face outside: %v\n", err)
 	} else {
 		report.Outward = links