MDL-35628 performance: Remove dirname() where possible.

dirname() is a slow function compared with __DIR__ and using
'/../'.  Moodle has a large number of legacy files that are included
each time a page loads and is not able to use an autoloader as it is
functional code.  This allows those required includes to perform as
best as possible in this situation.

mod/workshop/allocation/random/lib.php

@@ -28,9 +28,9 @@ defined('MOODLE_INTERNAL') || die();
 
 global $CFG;    // access to global variables during unit test
 
-require_once(dirname(dirname(__FILE__)) . '/lib.php');                  // interface definition
-require_once(dirname(dirname(dirname(__FILE__))) . '/locallib.php');    // workshop internal API
-require_once(dirname(__FILE__) . '/settings_form.php');                 // settings form
+require_once(__DIR__ . '/../lib.php');            // interface definition
+require_once(__DIR__ . '/../../locallib.php');    // workshop internal API
+require_once(__DIR__ . '/settings_form.php');     // settings form
 
 /**
  * Allocates the submissions randomly