RFR: 8294729: [s390] Implement nmethod entry barriers [v14]

[Tyler Steele]

On Thu, 27 Oct 2022 23:46:43 GMT, Tyler Steele <tsteele at openjdk.org> wrote:

>> This draft PR implements native method barriers on s390. When complete, this will fix the build, and bring the other benefits of [JDK-8290025](https://bugs.openjdk.org/browse/JDK-8290025) to that platform.
>
> Tyler Steele has refreshed the contents of this pull request, and previous commits have been removed. Incremental views are not available.

Apologies for the force-push and associated chaos. I believe the best course of action is to merge this PR as it was before the suggestions by fisk (which are appreciated nonetheless), as that PR solves the more immediate problem of fixing the build on s390.

I have incorporated fisk's suggestions in [a separate PR](https://github.com/openjdk/jdk/pull/10909), where I propose we continue development. In the new PR, I have integrated Martin & Lutz' improvements to my s390 assembly given in the reviews above.

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PR: https://git.openjdk.org/jdk/pull/10558