networkd: add minimal client tool "networkd" to query network status

In the long run this should become a full fledged client to networkd
(but not before networkd learns bus support). For now, just pull
interesting data out of networkd, udev, and rtnl and present it to the
user, in a simple but useful output.

src/machine/machine-dbus.c

@@ -207,7 +207,7 @@ int bus_machine_method_get_addresses(sd_bus *bus, sd_bus_message *message, void
                 if (r < 0)
                         _exit(EXIT_FAILURE);
 
-                n = local_addresses(&addresses);
+                n = local_addresses(NULL, 0, &addresses);
                 if (n < 0)
                         _exit(EXIT_FAILURE);