Fix test failure on Windows because of an extra warning

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42321 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
nmake doesn't out put targets

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42322 b2dd03c8-39d4-4d8f-98ff-823fe69b080e