Not from `ci->target_class` that may be switched using `class_eval` etc.
fix #3899, fix #3906

We found out there is a mruby specific limitation that `super` may be
screwed up when a method is defined in a module and `super` is called
in the block with the target class switched (for example, `super` in
`class_eval` block).  Now we raise `RuntimeError` for such cases.

The following code works in CRuby but not in mruby.
```
module M
  def foo
    "aaa".singleton_class.class_eval{super 2}
  end
end
class Foo
  def foo(*); end
end
class Bar<Foo
  include M
end
Bar.new.foo
```