(Bug 45355) Read of arbitrary files through mwdoc-filter.php

(Bug 45355) Read of arbitrary files through mwdoc-filter.php

The file maintenance/mwdoc-filter.php can be abused under certain server
configurations to read the contents of arbitrary files.

In case you
 - you have deleted the maintenance folder or
 - you have that folder denied in the server configuration or
 - the server is processing .htaccess overrides or
 - you are using PHP 5.4.0 (or later) or
 - you have register_globals disabled
it is believed that you are not vulnerable.

See https://bugzilla.wikimedia.org/45355 for details.

Change-Id: I3c49439b25896a6100ce415629353bccfc84490a