create branch 'DRUPAL-5'.

Sprout from master 2007-08-30 18:36:14 UTC Steve Rude <slantview@73183.no-reply.drupal.org> 'Updated apc after some testing with Drupal 6.'
Delete:
    session-apc-db.inc

This should be mostly working now, very much still alpha code however.

Added a lock and table lookup to keep track of objects in cache.
Need more testing.