在OS X安裝mcrypt

安裝就執行底下命令（php55-mcrypt非必要，只是我有這需求）

$brew install mcrypt php55-mcrypt

若之前有安裝過freetype，就會出現底下訊息

==> Installing php55-mcrypt from homebrew/homebrew-php
Error: You must `brew link freetype' before php55-mcrypt can be installed

執行底下命令

$brew link --overwrite freetype

回應如下

Linking /usr/local/Cellar/freetype/2.5.5... 8 symlinks created

再執行底下命令

$brew install  php55-mcrypt

回應如下

==> Installing php55-mcrypt from homebrew/homebrew-php
==> Installing php55-mcrypt dependency: autoconf
......以下省略

這樣就ok了

參考網址：
Installing mcrypt extension for PHP on OSX Mountain Lion
How to Install mcrypt for php on Mac OSX 10.9 Mavericks for a Development Server