RFR: 8360405: [PPC64] some environments don't support mfdscr instruction [v3]

[Richard Reingruber]

On Tue, 24 Jun 2025 18:53:17 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Add back `has_mfdscr()` checks which were recently removed. See https://github.com/openjdk/jdk/pull/20262#issuecomment-2999872960
>
> Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Newline.

Lgtm.
Cheers, Richard.

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Marked as reviewed by rrich (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25953#pullrequestreview-2957294349