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

Guo Wenxue

2019-06-26 74d93589a9de6c6c5158f122a2f73f6877a6317f

 apue/1.File_IO/ds18b20.c

@@ -116,5 +116,7 @@
    /* convert string value to float value */
    *temp = atof(ptr)/1000;
   
    close(fd);

    return 0;
}