RFR: 8307495: Specialize atomic bitset functions for aix-ppc [v8]

[Richard Reingruber]

On Mon, 13 Oct 2025 07:16:06 GMT, David Briemann <dbriemann at openjdk.org> wrote:

>> Add atomic bitset functions for PPC64.
>> Refactor so that inline assembler code is shared for all PPC64 platforms.
>> Add back a missing "simple guard" to PlatformCpmxchg<1>. Remove some dead Power7 code.
>
> David Briemann has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix typo

Marked as reviewed by rrich (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27650#pullrequestreview-3331468249