RFR(XXS) : 8179516 : add Utils.COMPILE_JDK constant

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8179516/webrev.00/index.html
> 5 lines changed: 5 ins; 0 del; 0 mod

Hi all,

could you please review this tiny fix which adds jdk.test.lib.Utils.COMPILE_JDK constant, which points to the JDK specified by '-compilejdk' jtreg flag or the JDK under test?

webrev: http://cr.openjdk.java.net/~iignatyev//8179516/webrev.00/index.html
JBS: https://bugs.openjdk.java.net/browse/JDK-8179516

Thanks,
-- Igor