specify unsigned (fix r58784).
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58788 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
specify unsigned (fix r58784).
Some compilers (includes VC) returns negative value.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58788 b2dd03c8-39d4-4d8f-98ff-823fe69b080e