RFR: CODETOOLS-7903004: JMH: Compiler Blackholes auto-detection

[Aleksey Shipilev]

This is another step towards better compiler blackholes support. This time, we can enable JMH to auto-detect the support and enable it, if JVM supports it.

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Commit messages:
 - CODETOOLS-7903004: JMH: Compiler Blackholes auto-detection

Changes: https://git.openjdk.java.net/jmh/pull/48/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmh&pr=48&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7903004
  Stats: 79 lines in 1 file changed: 73 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jmh/pull/48.diff
  Fetch: git fetch https://git.openjdk.java.net/jmh pull/48/head:pull/48

PR: https://git.openjdk.java.net/jmh/pull/48