RFR: 8268538: mark hotspot serviceability/logging tests which ignore external VM flags

[Igor Ignatyev]

Hi all,

could you please review the patch which adds `@requires vm.flagless` to serviceability/logging` tests that ignore external VM flags?

Thanks,
-- Igor

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Commit messages:
 - update copyright year
 - 8268538

Changes: https://git.openjdk.java.net/jdk/pull/4458/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4458&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268538
  Stats: 12 lines in 5 files changed: 6 ins; 1 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4458.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4458/head:pull/4458

PR: https://git.openjdk.java.net/jdk/pull/4458