update mqtt client

update mqtt client

components/connectivity/mqttclient/common/mqtt_error.h

@@ -2,12 +2,16 @@
  * @Author: jiejie
  * @Github: https://github.com/jiejieTop
  * @Date: 2019-12-15 00:42:16
- * @LastEditTime: 2020-04-27 23:35:05
+ * @LastEditTime: 2020-10-17 14:16:15
  * @Description: the code belongs to jiejie, please keep the author information and source code according to the license.
  */
 #ifndef _MQTT_ERROR_H_
 #define _MQTT_ERROR_H_
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef enum mqtt_error {
     MQTT_SSL_CERT_ERROR                                     = -0x001C,      /* cetr parse failed */
     MQTT_SOCKET_FAILED_ERROR                                = -0x001B,      /* socket fd failed */
@@ -42,4 +46,8 @@ typedef enum mqtt_error {
 
 #define RETURN_ERROR(x) { return x; }
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif