Bug 1653030: Using safe require auth saml

To make sure all dependent classes are included as well

behatnotneeded

Change-Id: Ib93776b163193849938619cbe9bbb7e073df7a02
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>

htdocs/lib/upgrade.php

@@ -1502,7 +1502,7 @@ function site_warnings() {
         $warnings[] = get_string('noreplyaddressmissingorinvalid', 'error', get_config('wwwroot') . 'admin/site/options.php?fs=emailsettings');
     }
 
-    require_once(get_config('docroot') . 'auth/saml/lib.php');
+    safe_require('auth', 'saml');
     if (PluginAuthSaml::is_active()) {
         // Check if the saml plugin config needs updating
         if (record_exists_select('auth_config', "plugin = ? AND field = ?", array('saml', 'simplesamlphplib'))) {