Fix memory leak when reconnecting with TLS errors.

Fix memory leak that occurred if mosquitto_reconnect() was used when TLS
errors were present.

Closes #592. Thanks to smartdabao and aaronovz1.

ChangeLog.txt

@@ -1,3 +1,11 @@
+1.5.4 - 201810xx
+================
+
+Library:
+- Fix memory leak that occurred if mosquitto_reconnect() was used when TLS
+errors were present. Closes #592.
+
+
 1.5.3 - 20180925
 ================
 

lib/net_mosq.c

@@ -596,6 +596,9 @@ int net__socket_connect_step3(struct mosquitto *mosq, const char *host, uint16_t
 	if(rc) return rc;
 
 	if(mosq->ssl_ctx){
+		if(mosq->ssl){
+			SSL_free(mosq->ssl);
+		}
 		mosq->ssl = SSL_new(mosq->ssl_ctx);
 		if(!mosq->ssl){
 			COMPAT_CLOSE(mosq->sock);