Updated jtreg build in the works ahead of JDK_MINOR_VERSION increment

[Joe Darcy]

FYI, one of the to-do items for early in a feature release is 
incrementing JDK_MINOR_VERSION, in the case of JDK 9, from "8" to "9". 
Test builds with this change revealed a bad interaction between the 
TestNG regression tests invoked through jtreg, leading to hundreds of 
the TestNGs tests in the langtools and jdk repositories spuriously 
failing after the increment. A fix for the jtreg issue is in the works; 
we're going to hold off pushing the JDK_MINOR_VERSION increment 
changeset until the corrected jtreg is available.

-Joe