When cleaning up the finalizers of a domain, do it in a way that reduces the chance...

When cleaning up the finalizers of a domain, do it in a way that reduces the chance of leftover objects.

	* gc.c (finalize_domain_objects): When cleaning up a domain, we run two kinds of finalizers,
	those that have already been queued and those for objects that remain alive.

	A common problem we need to deal is that some finalizers allocate other finalizable objects
	when doing seeminly trivial operations such as String.IndexOf - which might require the Thread
	object of the finalizer thread to be instantiated.

	We handle those new objects by draining the registered finalizers set until none shows up. This fails
	if we run the queued finalizers after that.

	The order onto which finalizers are run on domain unload is unspecified and the new behavior can
	be argued to be more natural.