use INT2FIX(0) instead of INT2NUM(0).

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39604 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-03-06

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39605 b2dd03c8-39d4-4d8f-98ff-823fe69b080e