* variable.c (set_const_visibility): use rb_frame_this_func() instead
  of rb_frame_callee() for getting the name of the called method

* test/ruby/test_module.rb: add test

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40915 b2dd03c8-39d4-4d8f-98ff-823fe69b080e