io.c: no error on frozen IO
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46151 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: no error on frozen IO
error on frozen IO. [ruby-dev:48241] [Bug #9865]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46151 b2dd03c8-39d4-4d8f-98ff-823fe69b080e