url is not required here

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48960 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* tool/downloader.rb: use config.guess in gcc repo.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48961 b2dd03c8-39d4-4d8f-98ff-823fe69b080e