Previously in some when classes were duped (specifically those with a
prepended module), they would not correctly have their "superclasses"
array or depth filled in.
This could cause ancestry checks (like is_a? and Module comparisons) to
return incorrect results.
This happened because rb_mod_init_copy builds origin classes in an order
that doesn't have the super linked list fully connected until it's
finished. This commit fixes the previous issue by calling
rb_class_update_superclasses before returning the cloned class. This is
similar to what's already done in make_metaclass.
