io.h: remove old macros
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53496 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.h: remove old macros
old macros only for internal use and obsolete since 2.2.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53496 b2dd03c8-39d4-4d8f-98ff-823fe69b080e