[jdk21u-dev] RFR: 8321269: Require platforms to define DEFAULT_CACHE_LINE_SIZE

[Aleksey Shipilev]

Clean backport to improve platform support. Unblocks future backports that rely on default cache line size.

-------------

Commit messages:
 - Backport a56286f7ad9a8110026f48eb45f1d7a273b2f9fb

Changes: https://git.openjdk.org/jdk21u-dev/pull/150/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=150&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321269
  Stats: 7 lines in 4 files changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/150.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/150/head:pull/150

PR: https://git.openjdk.org/jdk21u-dev/pull/150