MINOR: server: cli: Add server FQDNs to server-state file and stats socket.

This patch adds a new stats socket command to modify server
FQDNs at run time.
Its syntax:
  set server <backend>/<server> fqdn <FQDN>
This patch also adds FQDNs to server state file at the end
of each line for backward compatibility ("-" if not present).
diff --git a/src/proxy.c b/src/proxy.c
index dc70213..f6a3214 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -1458,13 +1458,13 @@
 				"%d %s %s "
 				"%d %d %d %d %ld "
 				"%d %d %d %d %d "
-				"%d %d"
+				"%d %d %s"
 				"\n",
 				px->uuid, px->id,
 				srv->puid, srv->id, srv_addr,
 				srv->state, srv->admin, srv->uweight, srv->iweight, (long int)srv_time_since_last_change,
 				srv->check.status, srv->check.result, srv->check.health, srv->check.state, srv->agent.state,
-				bk_f_forced_id, srv_f_forced_id);
+				bk_f_forced_id, srv_f_forced_id, srv->hostname ? srv->hostname : "-");
 		if (bi_putchk(si_ic(si), &trash) == -1) {
 			si_applet_cant_put(si);
 			return 0;