Centos安装PHP时，安装php依赖包时yum install libmcrypt libmcrypt-devel，报错如下：
No package libmcrypt available. No package libmcrypt-devel available. Error: Nothing to do
然后编译的时候，又报错：
checking for mcrypt support... yes configure: error: mcrypt.h not found. Please reinstall libmcrypt.
解决方法：yum install epel-release //扩展包更新包