Now that we do not need the new object while holding the highly trafficed

Now that we do not need the new object while holding the highly trafficed
objhead lock, don't preallocate objects.

One unfortunate effect of this preallocation, only recently identified:

On systems with high number of worker threads and high hitrates, considerable
time could elapse between the preallocation of an object to a worker
thread and the use of that object.

This could make cache-misses use a much larger working set size than
really necessary.

I do not have access to any benchmarks that show a credible performance
difference, but reports are most welcome.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@3842 d4fa192b-c00b-0410-8231-f00ffab90ce4