Add a nag message for themes which are relying on the deprecated behaviour.

git-svn-id: https://develop.svn.wordpress.org/trunk@14369 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/themes.php

@@ -59,8 +59,8 @@ if ( is_multisite() && current_user_can('edit_themes') ) {
 	elseif ( isset($_GET['deleted']) ) : ?>
 <div id="message3" class="updated"><p><?php _e('Theme deleted.') ?></p></div>
 <?php endif; ?>
-
 <?php
+_check_theme_deprecated_files();
 $themes = get_allowed_themes();
 $ct = current_theme_info();
 unset($themes[$ct->name]);