sd-dhcp-client: don't fail hard if UDP socket can not be bound

Even if we cannot renew the lease at T1, we will likely succeed at T2, so warn and ignore the failure.

This could happen if for whatever reason the received address is not yet configured, or it has
been lost.

src/libsystemd-network/sd-dhcp-client.c

@@ -776,7 +776,7 @@ static int client_timeout_t1(sd_event_source *s, uint64_t usec,
         r = dhcp_network_bind_udp_socket(client->lease->address,
                                          DHCP_PORT_CLIENT);
         if (r < 0) {
-                client_stop(client, r);
+                log_dhcp_client(client, "could not bind UDP socket");
                 return 0;
         }