add htmlentities() call into login form

core/templates/login.php

 <!--[if IE 8]><style>input[type="checkbox"]{padding:0;}</style><![endif]-->
 <form action="index.php" method="post">
 	<fieldset>
-		<?php if(!empty($_['redirect'])) { echo '<input type="hidden" name="redirect_url" value="'.$_['redirect'].'" />'; } ?>
+		<?php if(!empty($_['redirect'])) { echo '<input type="hidden" name="redirect_url" value="'.htmlentities($_['redirect']).'" />'; } ?>
 		<?php if($_['error']): ?>
 			<a href="./core/lostpassword/"><?php echo $l->t('Lost your password?'); ?></a>
 		<?php endif; ?>