split clear mechanisms in 5 & 6

platform/drupal/clear_5.inc

+<?php
+// $Id$
+/**
+ *  @file
+ *    Rebuild all the caches
+ */
+cache_clear_all();
+drush_log(t('Cleared all caches'));
+
+node_types_rebuild();
+drush_log(t('Rebuild node type cache'));
+
+module_rebuild_cache();
+drush_log(t('Rebuild module cache'));
+
+system_theme_data();
+drush_log(t('Rebuild theme cache'));
+
+node_access_rebuild();
+drush_log(t('Rebuild node access cache'));
+
+menu_rebuild();
+drush_log(t('Rebuild menu cache'));