RFR: 7902762: JMH: Use "blackhole" compiler command [v3]

[Aleksey Shipilev]

> JMH can be enabled to use the "blackhole" compile command from [JDK-8252505](https://bugs.openjdk.java.net/browse/JDK-8252505).

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Touchups

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

Changes:
  - all: https://git.openjdk.java.net/jmh/pull/8/files
  - new: https://git.openjdk.java.net/jmh/pull/8/files/13081a59..707bc782

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmh&pr=8&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jmh&pr=8&range=01-02

  Stats: 15 lines in 4 files changed: 1 ins; 2 del; 12 mod
  Patch: https://git.openjdk.java.net/jmh/pull/8.diff
  Fetch: git fetch https://git.openjdk.java.net/jmh pull/8/head:pull/8

PR: https://git.openjdk.java.net/jmh/pull/8