Make HSH_Deref return the busyobj to the worker for reuse when dereferencing and destroying a busy objcore.
Make HSH_Deref return the busyobj to the worker for reuse when
dereferencing and destroying a busy objcore.

Free the busyobj in the case that the worker already has one
(potential race condition from the expiry/ban-lurker threads?)

ssm/pkg-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish