require fixtures/classes only when platform is windows.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65416 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
require fixtures/classes only when platform is windows.
because this file is required when platform is Windows.
fixtures/classes is required when platform is Windows
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65416 b2dd03c8-39d4-4d8f-98ff-823fe69b080e