[jdk26] RFR: 8373630: r18_tls should not be modified on Windows AArch64

[Saint Wesonga]

This pull request is a backport of commit [a0dd66f9](https://github.com/openjdk/jdk/commit/a0dd66f92d7f8400b9800847e36d036315628afb)

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Commit messages:
 - Backport a0dd66f92d7f8400b9800847e36d036315628afb

Changes: https://git.openjdk.org/jdk/pull/28933/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28933&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373630
  Stats: 23 lines in 1 file changed: 23 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28933.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28933/head:pull/28933

PR: https://git.openjdk.org/jdk/pull/28933