references:
http://stackoverflow.com/questions/21047399/cmake-set-environment-variables-from-a-script
http://stackoverflow.com/questions/7584602/how-to-set-path-environment-variable-in-cmake-script
Cmake设置环境变量,布布扣,bubuko.com
Cmake设置环境变量
原文：http://www.cnblogs.com/foohack/p/3569445.html
