hg: jdk/sandbox: 8210511: TestSingleWriterSynchronizer can deadlock

[chris.hegarty at oracle.com]

Changeset: b83571bbc147
Author:    kbarrett
Date:      2018-09-10 19:18 -0400
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/b83571bbc147

8210511: TestSingleWriterSynchronizer can deadlock
Summary: Check for safepoints in test loops.
Reviewed-by: coleenp, eosterlund

! test/hotspot/gtest/utilities/test_singleWriterSynchronizer.cpp