Add support for JRuby 9000 dev bundled with the Graal VM.

JRuby 9000 (the next major release) includes a backend that supports a new JVM JIT compiler called Graal. Graal is based on OpenJDK but hasn't been released yet. This patch allows you to download Graal with JRuby and have JRuby already configured to use it instead of your system Java.

http://openjdk.java.net/projects/graal/

I know this is a bit niche, but I promise to keep it updated, and remove it if it's not longer applicable.