RFR: 7904042: jcstress: Native access warnings when running with JDK 25

[Aleksey Shipilev]

Current jcstress uses JNA for affinity setup. It causes lots of warnings when running with JDK 25.

This PR tries to fix most of them.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jcstress/pull/171/files
  Webrev: https://webrevs.openjdk.org/?repo=jcstress&pr=171&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7904042
  Stats: 33 lines in 5 files changed: 30 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jcstress/pull/171.diff
  Fetch: git fetch https://git.openjdk.org/jcstress.git pull/171/head:pull/171

PR: https://git.openjdk.org/jcstress/pull/171