git: openjdk/loom: fibers: Fix some ObjectReference tests that failed due to having one fewer references than expected. The missing reference is due to ThreadGroup no longer referring to each Thread.

[duke]

Changeset: 5ab3ac63
Author:    Chris Plummer <chris.plummer at oracle.com>
Date:      2021-09-08 04:51:41 +0000
URL:       https://git.openjdk.java.net/loom/commit/5ab3ac63988ed62d061c337ea99e283487b441b7

Fix some ObjectReference tests that failed due to having one fewer references than expected. The missing reference is due to ThreadGroup no longer referring to each Thread.

! test/hotspot/jtreg/ProblemList-vthread.txt
! test/hotspot/jtreg/vmTestbase/nsk/jdi/ObjectReference/referringObjects/referringObjects003/referringObjects003.java