update iotd 3rdlib build shell script for cjson

guowenxue

2021-05-02 aed475c7a57e329a3e90cce56d00ca997f519cda

tools/rpi_crosstool.tar.bz2 does not exist in tree 71dd9e39349c45595c84eeedbd8d3dabda1a4ca9