Fix up r57788, Function is removed at readline-6.3.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57794 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Fix up r57788, Function is removed at readline-6.3.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57794 b2dd03c8-39d4-4d8f-98ff-823fe69b080e