I know this is a very old post, but it just helped me along my path and so I'm leaving the tidbit I (believe) I just learned for the next poor devil encountering the same thing.
I believe you need the php-devel package for phpize to work.
yum -y install php-devel
I'm not 100 percent sure of the syntax to install php-devel in Darwin (mac), but the principle will follow the above.
Hope this helps somebody.