io.c: ID instead of Symbol

* io.c (get_kwargs_exception): rb_get_kwargs() expects IDs, but
  not Symbols.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47804 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-10-06

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47805 b2dd03c8-39d4-4d8f-98ff-823fe69b080e