RFR: CODETOOLS-7903003: JMH: Print a single interruption message per iteration

[Aleksey Shipilev]

When harness interrupts the benchmark, it delivers several interrupts until the benchmark exits. Every time on interrupt, it will print a message, which can flood the logs. We are better printing the interrupt message one time.

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Commit messages:
 - CODETOOLS-7903003: JMH: Print a single interruption message per iteration

Changes: https://git.openjdk.java.net/jmh/pull/47/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmh&pr=47&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7903003
  Stats: 7 lines in 1 file changed: 6 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jmh/pull/47.diff
  Fetch: git fetch https://git.openjdk.java.net/jmh pull/47/head:pull/47

PR: https://git.openjdk.java.net/jmh/pull/47