Fix incorrect 'socket' value for new (highwater) log message

src/sbbs3/main.cpp

@@ -5924,7 +5924,7 @@ NO_SSH:
 			client_highwater = client_count;
 			if(client_highwater > 1)
 				lprintf(LOG_NOTICE, "%04d New active client highwater mark: %u"
-					,socket, client_highwater);
+					,client_socket, client_highwater);
 			mqtt_pub_uintval(&mqtt, TOPIC_SERVER, "highwater", client_highwater);
 		}
 	}