Fixed threaded enum lost in merges

Change was part of the original commit e8185ddaa7
"[166] Don't cancel external threads."
and then lost during code reorganizing and subsequent merge,
commits 970ba58da6 81cb7ab547

Signed-off-by: Maksym Ruchko <mruchko@advantech-bb.com>

lib/packet_mosq.c

@@ -141,7 +141,7 @@ int packet__queue(struct mosquitto *mosq, struct mosquitto__packet *packet)
 #endif
 	}
 
-	if(mosq->in_callback == false && mosq->threaded == false){
+	if(mosq->in_callback == false && mosq->threaded == mosq_ts_none){
 		return packet__write(mosq);
 	}else{
 		return MOSQ_ERR_SUCCESS;