hg: shenandoah/jdk8u/hotspot: [backport] Add "verify jcstress" acceptance test

[ashipile at redhat.com]

Changeset: 09ff92792fd5
Author:    shade
Date:      2017-07-17 13:15 +0200
URL:       http://hg.openjdk.java.net/shenandoah/jdk8u/hotspot/rev/09ff92792fd5

[backport] Add "verify jcstress" acceptance test

+ test/gc/shenandoah/acceptance/VerifyJCStressTest.java