using the objhead as carrier for it.

The time difference between objhead freeing and Y freeing is very
significant on systems with rolling URLS (ie: "article=%d") resulting
in far too many objheads being stuck on the cooling list.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4859 d4fa192b-c00b-0410-8231-f00ffab90ce4