出现：error: openssl/md5.h: No such file or directory
原因是openssl-devel没有安装，运行：
yum install libssl-dev 就能够了
我用的Fodera找不到libssl-dev，就运行yum install openssl openssl-devel
linux下apache+php安装常见问题
http://hi.baidu.com/easyphp/item/f0e4064c21679deea4c066c9
2) Checking for pkg-config… /usr/bin/pkg-config
configure: error: Cannot find OpenSSL’s <evp.h>
Solutions :
apt-get install libssl-dev(UBUNTU)
Quote: #yum install openssl openssl-devel