Originally we shaved 64 bytes from the session to the worker thread

Originally we shaved 64 bytes from the session to the worker thread
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: svn+ssh://projects.linpro.no/svn/varnish/trunk@3512 d4fa192b-c00b-0410-8231-f00ffab90ce4