vm_method.c: constify

* vm_method.c (rb_resolve_refined_method): constify.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42902 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
class.c: exclude refined methods

* class.c (method_entry_i): should exclude refined methods from
  instance method list.  [ruby-core:57080] [Bug #8881]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42903 b2dd03c8-39d4-4d8f-98ff-823fe69b080e