Add gpiod.c for libgpiod output sample code

guowenxue

2021-01-23 7baed996272cd3c889a5ab714c2b3391703f75f1

 modules/c/makefile

@@ -18,8 +18,13 @@
CFLAGS+=-I${PWD}
#CFLAGS+=-Wall -Werror

# default use libgpiod library
#CFLAGS+=-DCONFIG_USE_WIRINGPI

LDFLAGS+=-lwiringPi
LDFLAGS+=-lgpiod
LDFLAGS+=-lpthread
LDFLAGS+=-lm

VPATH= .
SRCS = $(wildcard ${VPATH}/*.c)