hg: jdk10/sandbox/langtools: 8186095: upgrade to jtreg 4.2 b08

[chris.hegarty at oracle.com]

Changeset: c286cfbac9ff
Author:    iignatyev
Date:      2017-08-20 20:36 -0700
URL:       http://hg.openjdk.java.net/jdk10/sandbox/langtools/rev/c286cfbac9ff

8186095: upgrade to jtreg 4.2 b08
Reviewed-by: rriggs, mchung, dholmes, iklam

! test/TEST.ROOT