io.c: fix local variables
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60351 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: fix local variables
writev(2) is not available. [Feature #9323]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60351 b2dd03c8-39d4-4d8f-98ff-823fe69b080e