MINOR: server: new server flag: SRV_F_FORCED_ID

This flag aims at reporting whether the server unique id (srv->puid) has
been forced by the administrator in HAProxy's configuration.
If not set, it means HAProxy has generated automatically the server's
unique id.

src/server.c

@@ -161,6 +161,7 @@ static int srv_parse_id(char **args, int *cur_arg, struct proxy *curproxy, struc
 	}
 
 	eb32_insert(&curproxy->conf.used_server_id, &newsrv->conf.id);
+	newsrv->flags |= SRV_F_FORCED_ID;
 	return 0;
 }