xml4r/libxml-ruby — pull request #99 by hainesr (2014-11-27 17:30:31+00:00)
Title: Use RbConfig instead of Config in extconf.rb.

```Config``` has been deprecated for a while and now is gone from ruby 2.2 so libxml-ruby does not build in ruby 2.2.

```RbConfig``` is the advised fix.