Merge json-2.1.0 from https://github.com/flori/json
https://github.com/flori/json/blob/master/CHANGES.md#2017-04-18-210
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59099 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Merge json-2.1.0 from https://github.com/flori/json
https://github.com/flori/json/blob/master/CHANGES.md#2017-04-18-210
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59099 b2dd03c8-39d4-4d8f-98ff-823fe69b080e