checking for libmcrypt – version >= 2.5.0…*** ‘libmcrypt-config –version’ returned 2.4.0, but LIBMCRYPT (2.5.8)*** was found! If libmcrypt-config was correct, then it is best*** to remove the old version of LIBMCRYPT. You may also be able to fix the error*** by modifying your LD_LIBRARY_PATH enviroment variable, or by editing*** /etc/ld.so.conf. Make sure you have run ldconfig if that is*** required on your system.*** If libmcrypt-config was wrong, set the environment variable LIBMCRYPT_CONFIG*** to point to the correct copy of libmcrypt-config, and remove the file config.cache*** before re-running configureconfigure: error: *** libmcrypt was not found
分析：
明明我安装了libmcrypt 2.5.8 ，可是竟然提示没有发现！然后在/usr/local/bin/找到了LIBMCRYPT_CONFIG ，这一步明确了是PATH变量的问题 ！
解决方法：
ln -s /usr/local/lib/libmcrypt.la /usr/lib/libmcrypt.laln -s /usr/local/lib/libmcrypt.so /usr/lib/libmcrypt.soln -s /usr/local/lib/libmcrypt.so.4 /usr/lib/libmcrypt.so.4ln -s /usr/local/lib/libmcrypt.so.4.4.8 /usr/lib/libmcrypt.so.4.4.8
ln -s /usr/local/bin/libmcrypt-config /usr/bin/libmcrypt-config
原文：http://www.ieliwb.com/centos-libmcrypt-not-found/
