RFR: 8307483: New micros for j.u.c.LockSupport

[Eric Caspole]

These micros were developed while investigating JDK-8305670 by myself and Sergey Kuksenko. The order of thread creation was important in that bug, so there are 2 JMH for creating sleepers before and after the worker threads.

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Commit messages:
 - 8307483: New micros for j.u.c.LockSupport

Changes: https://git.openjdk.org/jdk/pull/13815/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13815&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307483
  Stats: 274 lines in 2 files changed: 274 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13815.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13815/head:pull/13815

PR: https://git.openjdk.org/jdk/pull/13815