add and add mqttd proc.c and main.c, set 3 threads running

guowenxue

2019-06-25 0c6d37d6eb4eae9a91c7433adc7e76ba54c67c0f

tools/rpi_crosstool.tar.bz2 does not exist in tree ee1b8d81bacaa55698a5d6b6b85998e6e05934ec