don't report PERSISTENCE STATUS in reg burst for anonymous clients

irc/server.go

 
 	rb := NewResponseBuffer(session)
 	server.RplISupport(c, rb)
-	if session.capabilities.Has(caps.Persistence) {
+	if d.account != "" && session.capabilities.Has(caps.Persistence) {
 		reportPersistenceStatus(c, rb)
 	}
 	server.Lusers(c, rb)