a doubly-linked list, exposed by sys.getobjects().  Unfortunately, it's not
really all live objects, and it seems my fate to bump into programs where
sys.gettotalrefcount() keeps going up but where the reference leaks aren't
accounted for by anything in the list of all objects.

This patch helps a little:  if COUNT_ALLOCS is also defined, from now on
type objects will also appear in this list, provided at least one object
of a type has been allocated.