update mqttd program, fix rpi build bug for strcasestr()

Guo Wenxue

2019-06-26 74d93589a9de6c6c5158f122a2f73f6877a6317f

tools/rpi_crosstool.tar.bz2 does not exist in tree 0b6f8310229ab738060179d512fe15322a8c42c8