Can't phpize or configure an extension in OS X 10.9 Mavericks
run xcode-select --install to install the XCode5 Command Line Tools, then sudo pecl install memcache. You should be good to go.
After install XCode5 Command Line Tools as afessler sugest (xcode-select --install) I couldn't do the "sudo pecl install memcache" because pecl was missing.I had to install PEAR and PECL following this guide: http://techtastico.com/post/como-instalar-pear-y-pecl-en-os-x-mavericks/.Then all worked good. Thanks!
I had this problem and it was due to MAMP not having all the PHP sources.
I found this really helpful solution that explains how to download and configure them:https://stackoverflow.com/a/11175197/369326
Note that the MAMP components doesn't include the extras for any versions of PHP higher than php 5.4.10 but you can download the extras from http://php.net/releases.