RFR: 8271829: mark hotspot runtime/Throwable tests which ignore external VM flags

[Igor Ignatyev]

Hi all,

could you please review the patch that adds `@requires vm.flagless` to three `runtime/Throwable` tests?

Thanks,
-- Igor

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Commit messages:
 - copyright year
 - 8271829

Changes: https://git.openjdk.java.net/jdk/pull/4985/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4985&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271829
  Stats: 5 lines in 3 files changed: 3 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4985.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4985/head:pull/4985

PR: https://git.openjdk.java.net/jdk/pull/4985