Compile error building FX with latest JDK

[Kevin Rushforth]

All,

There is a bug in JDK 8, introduced in b108, that will cause a clean 
build of FX to fail.

https://bugs.openjdk.java.net/browse/JDK-8025173

It is expected that this will be fixed in b110.

Until then, you can either stick with an older JDK, or use the following 
workaround, to compile the buildSrc part of the project with an older JDK:

    # point to older JDK
    gradle clean
    # point to latest JDK
    gradle

-- Kevin