RFR: 8271891: mark hotspot runtime/Safepoint tests which ignore external VM flags

[Igor Ignatyev]

Hi all,

please review this small patch that `@requires vm.flagless` to `runtime/Safepoint` tests.

Thanks,
-- Igor

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Commit messages:
 - 8271891

Changes: https://git.openjdk.java.net/jdk/pull/5000/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5000&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271891
  Stats: 2 lines in 2 files changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5000.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5000/head:pull/5000

PR: https://git.openjdk.java.net/jdk/pull/5000