hg: zgc/zgc: ZGC: Rework comment about broken test

[per.liden at oracle.com]

Changeset: 1e4e97efc975
Author:    pliden
Date:      2018-06-05 11:50 +0200
URL:       http://hg.openjdk.java.net/zgc/zgc/rev/1e4e97efc975

ZGC: Rework comment about broken test

! test/hotspot/jtreg/vmTestbase/nsk/jdi/ObjectReference/referringObjects/referringObjects001/referringObjects001.java
! test/hotspot/jtreg/vmTestbase/nsk/jdi/ReferenceType/instances/instances003/instances003.java
! test/hotspot/jtreg/vmTestbase/nsk/jdwp/ReferenceType/Instances/instances001/instances001.java
! test/hotspot/jtreg/vmTestbase/nsk/jdwp/VirtualMachine/InstanceCounts/instanceCounts001/instanceCounts001.java