daemon: Always advertise libvirtd service

This is a regression introduced by new RPC codes, previously
we advertise the service via ssh even if the daemon doesn't
listen on TLS port (TCP is not choosed). Now the service is
only advertised when it listens on TLS or TCP port. This breaks
upper layer apps which intends to discover the service, such
as virt-manager.

daemon/libvirtd.c

@@ -470,8 +470,12 @@ static int daemonSetupNetworking(virNetServerPtr srv,
                                              NULL)))
         goto error;
 
-    if (virNetServerAddService(srv, svc, NULL) < 0)
+    if (virNetServerAddService(srv, svc,
+                               config->mdns_adv && !ipsock ?
+                               "_libvirt._tcp" :
+                               NULL) < 0)
         goto error;
+
     if (svcRO &&
         virNetServerAddService(srv, svcRO, NULL) < 0)
         goto error;