RFR: 8355445: [java.nio] Use @requires tag instead of exiting based on os.name property value

[Brian Burkhalter]

Use the `@requires` tag instead of obtaining the operating system name from the `os.name` property and then exiting if the test is not run on that operating system.

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Commit messages:
 - 8355445: [java.nio] Use @requires tag instead of exiting based on os.name property value

Changes: https://git.openjdk.org/jdk/pull/24861/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24861&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355445
  Stats: 55 lines in 8 files changed: 7 ins; 33 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/24861.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24861/head:pull/24861

PR: https://git.openjdk.org/jdk/pull/24861