I'd like to further this thread to as a request for help w/Ubuntu instructions to get the Piwik module to show installed in the Piwik control panel. [AWS Bitnami 3.0.2 - Ubuntu 14.04.03]
My attempt was as follows:
apt-get install php5-geoip php5-dev libgeoip-dev
Note: Unless you proceed with the PECL install as below the above requires you to locate geoip.so and manually copy to php extensions. [This gets the Piwik GeoPhp function working] You'll need to chmod/chown the directory and file as this is root, set to bitnami, and then set it back to root:root.
pecl install geoip
pecl config-set php_ini /opt/bitnami/php/etc/php.ini