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

[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`

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Commit messages:
 - Backport f85411f24a0cf55f8718aadd2297d95feb95564b

Changes: https://git.openjdk.org/jdk17u-dev/pull/1948/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1948&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292458
  Stats: 126 lines in 4 files changed: 113 ins; 0 del; 13 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