use timeout lib

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48977 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-12-25

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48978 b2dd03c8-39d4-4d8f-98ff-823fe69b080e