RFR: 8375622: G1: Convert G1CodeRootSet to use Atomic<T> [v2]

[Thomas Schatzl]

> Hi all,
> 
>   please review this change to convert `G1CodeRootSet` to use `Atomic<T>` instead of `AtomicAccess`.
> 
> Testing: gha,
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  * shade review

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/29296/files
  - new: https://git.openjdk.org/jdk/pull/29296/files/b76b4df8..ce402ea6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29296&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29296&range=00-01

  Stats: 3 lines in 2 files changed: 1 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29296.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29296/head:pull/29296

PR: https://git.openjdk.org/jdk/pull/29296