RFR: 8373118: Test java/lang/Thread/virtual/Starvation.java timed out

[Doug Lea]

Changes signal filtering to avoid possible starvation

-------------

Commit messages:
 - signalWork diagnostic
 - filter by index
 - For testing

Changes: https://git.openjdk.org/jdk/pull/28797/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28797&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373118
  Stats: 70 lines in 1 file changed: 44 ins; 5 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/28797.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28797/head:pull/28797

PR: https://git.openjdk.org/jdk/pull/28797