MAX_IV_COUNT is a hint which determines the size of variable width allocation we should use for a given class. We don't need to scope this by namespace, if we end up with larger builtin objects on some namespaces that isn't a user-visible problem, just extra memory use. Similarly variation_count is used to track if a given object has had too many branches in shapes it has used, and to use too_complex when that happens. That's also just a hint, so we can use the same value across namespaces without it being visible to users. Previously variation_count was being incremented (written to) on the RCLASS_EXT_READABLE ext, which seems incorrect if we wanted it to be different across namespaces