* eval.c (Init_eval): main.include should be private.
  [ruby-core:51293] [Bug #7670]

* test/ruby/test_module.rb (test_top_include_is_private): a new test
  for the above change.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38731 b2dd03c8-39d4-4d8f-98ff-823fe69b080e