[9] Review request: 8133750: Parse new JDK version string format in build.gradle

[Kevin Rushforth]

Chien, David, and all,

Please review the version string changes in build.gradle to prepare for 
using a JDK 9 with the new version string format for JEP 223 (aka Verona).

https://bugs.openjdk.java.net/browse/JDK-8133750
http://cr.openjdk.java.net/~kcr/8133750/webrev.00/

I have tested this with a JDK 8u40 fcs build, 8u45 fcs build, jdk8u-dev 
local build, JDK 9 pre-Verona ea build, JDK 9-ea+96 post-Verona build, 
and a local jdk9-dev build.

-- Kevin