* vm_method.c (Init_eval_method): main.public and main.private
  should be private.

* proc.c (Init_Proc): main.define_method should be private.

* test/ruby/test_module.rb: related test.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38732 b2dd03c8-39d4-4d8f-98ff-823fe69b080e