[jdk17u-dev] RFR: 8292458: Atomic operations on scoped enums don't build with clang [v3]

[Aleksey Shipilev]

> Clean backport to improve native atomics support. This does not fix any currently observed bugs, but it should provide more safety for backports that would use scoped enums and clang. It also makes subsequent backports cleaner. There is no bugtail recorded for this improvement, after more than a year in mainline.
> 
> Additional testing:
>  - [x] MacOS AArch64 server fastdebug, `tier1`

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'master' into JDK-8292458-atomic-scoped-enums
 - Merge branch 'master' into JDK-8292458-atomic-scoped-enums
 - Backport f85411f24a0cf55f8718aadd2297d95feb95564b

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

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/1948/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/1948/files/574b5d40..bff47966

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1948&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1948&range=01-02

  Stats: 16964 lines in 307 files changed: 9001 ins; 3183 del; 4780 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1948.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1948/head:pull/1948

PR: https://git.openjdk.org/jdk17u-dev/pull/1948