by keeping the current requests accounting stats in the worker thread.

For reasons which will be explained in the next commit, this is no
longer a good idea, and this commit moves these counters from
the worker thread to the session at a slight but all in all
trivial cost in memory footprint.

Remove the call to SES_Charge() when we hit a busy object, it is
not necessary to clean the worker thread counters here now.

Move these counters from the worker thread to the see


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3512 d4fa192b-c00b-0410-8231-f00ffab90ce4