fixed another trigger recursion when updating a cache record

function touchCache() in lib/clicompatbase.inc.php updated e.g. cache_desc.last_modified
in the same statement with an access to caches table. As the cacheDescAfterUpdate trigger
updates caches.last_modified, the read & write access to caches table collided.

function touchCache() is obsolete, as touching on status change is done by triggers
for all depending tables (via SQL function sp_touch_cache).