RFR: 8359127: Amend java/nio/channels/DatagramChannel/PromiscuousIPv6.java to use @requires for OS platform selection

[Dermot Boyle]

Replaced programmatic check for the OS platform (which threw a Skipped exception) with JTreg @requires.

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Commit messages:
 - Update coopyright header
 - JDK-8359127: Amend java/nio/channels/DatagramChannel/PromiscuousIPv6.java to use @requires for OS platform selection

Changes: https://git.openjdk.org/jdk/pull/25781/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25781&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359127
  Stats: 11 lines in 1 file changed: 1 ins; 4 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/25781.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25781/head:pull/25781

PR: https://git.openjdk.org/jdk/pull/25781