Don't keep trying to connect in sub client if CONNACK negative.

ChangeLog.txt

@@ -101,6 +101,8 @@ Clients:
 - Connections now default to using MQTT v3.1.1.
 - Default to using port 8883 when using TLS.
 - Correctly handle empty files with "mosquitto_pub -l". Closes #676.
+- mosquitto_sub doesn't continue to keep connecting if CONNACK tells it the
+  connection was refused.
 
 Build:
 - Add WITH_STRIP option (defaulting to "no") that when set to "yes" will strip

client/sub_client.c

@@ -367,6 +367,7 @@ void my_connect_callback(struct mosquitto *mosq, void *obj, int result)
 		if(result && !cfg->quiet){
 			fprintf(stderr, "%s\n", mosquitto_connack_string(result));
 		}
+		mosquitto_disconnect(mosq);
 	}
 }