io.c: enclose statements by ifdef
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48050 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: enclose statements by ifdef
ifdef, not only a case label.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48050 b2dd03c8-39d4-4d8f-98ff-823fe69b080e