Admin checks: fix HTML syntax error on index page

A closing </div> was missing when displaying failures or warning.

admin/check/index.php

@@ -202,6 +202,8 @@ function mode_url( $p_all, $p_errors ) {
 <div class="alert alert-success"  id="check-notice-passed">
 	All tests passed.
 </div>
+<?php } ?>
+
 </div>
-<?php }
+<?php
 layout_admin_page_end();