io.c: remove socket check
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44747 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: remove socket check
[ruby-core:59856][Feature #9427]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44747 b2dd03c8-39d4-4d8f-98ff-823fe69b080e