This class is an authorization plugin for Mediawiki. It performs the
authorization and user existence queries to an arbitrary MySQL
database. An example of its use is included in the
LocalSettings.third_party_db_auth.php file.

To use the plugin, you could either 'require' the
LocalSettings.third_party_db_auth.php file in your LocalSettings.php,
or copy-and-paste its contents into LocalSettings.php, somewhere near
the bottom (after DefaultSettings.php is included).