[jdk17u-dev] RFR: 8307926: Support byte-sized atomic bitset operations

[Aleksey Shipilev]

Clean backport to improve Atomic support in JDK 17 and align it with mainline JDKs, simplifying future backports. Note the patch basically adds documentation that byte-level support is available, and adds a few tests. Therefore, there is no direct product impact.

Additional testing:
 - [x] macos-aarch64-server-fastdebug, `Atomic` gtests

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Commit messages:
 - Backport 646747fd7c7320910eed682ae6da3cd4c60a51a5

Changes: https://git.openjdk.org/jdk17u-dev/pull/2061/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2061&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307926
  Stats: 17 lines in 2 files changed: 14 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2061.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2061/head:pull/2061

PR: https://git.openjdk.org/jdk17u-dev/pull/2061