[jdk17u-dev] RFR: 8295124: Atomic::add to pointer type may return wrong value

[Aleksey Shipilev]

Clean backport to improve Atomics support. Important to get it right to avoid future backporting accidents.

Additional testing:
 - [x] New testcases fail without the fix, pass with it
 - [x] Linux x86_64 server fastdebug, `tier1`
 - [ ] Linux AArch64 server fastdebug, `tier1`

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Commit messages:
 - Backport 1164258ec7d173944f48cba368d6c50a07b4c283

Changes: https://git.openjdk.org/jdk17u-dev/pull/2043/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2043&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295124
  Stats: 167 lines in 2 files changed: 152 ins; 3 del; 12 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2043.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2043/head:pull/2043

PR: https://git.openjdk.org/jdk17u-dev/pull/2043