RFR: CODETOOLS-7902915: JMH: Use Console.charset() if available

[Aleksey Shipilev]

JDK-8264208 added a public method to poll the Console charset. We can use it in JMH code that detects Console charset, when available.

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Commit messages:
 - CODETOOLS-7902915: JMH: Use Console.charset() if available

Changes: https://git.openjdk.java.net/jmh/pull/34/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmh&pr=34&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7902915
  Stats: 22 lines in 1 file changed: 12 ins; 0 del; 10 mod
  Patch: https://git.openjdk.java.net/jmh/pull/34.diff
  Fetch: git fetch https://git.openjdk.java.net/jmh pull/34/head:pull/34

PR: https://git.openjdk.java.net/jmh/pull/34