Add gpiod.c for libgpiod output sample code

guowenxue

2021-01-23 7baed996272cd3c889a5ab714c2b3391703f75f1

 mqttd/hal/sht20.h

@@ -13,6 +13,7 @@
#ifndef __SHT20_H
#define __SHT20_H

#include <stdio.h>
#include <stdint.h>
#include <time.h>