RFR: 8307907: [ppc] Remove RTM locking implementation [v5]

[Thomas Stuefe]

On Wed, 14 Jun 2023 22:24:53 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> This PR removes RTM code for PPC64. The instructions are not supported by Power10 processors.
>> The situation is even worse in Power9 compatibility mode on Power10. The VM detects RTM to be available, but the processor is unable to complete any transaction successfully.
>> The feature had so many problems and we never supported it in production.
>
> Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove RTM_OS_ERROR which is no longer used.

This is a nice complexity reduction!

All good now.

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Marked as reviewed by stuefe (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14398#pullrequestreview-1480685000