RFR: 8367325: [s390x] build failure due to JDK-8361376

[Martin Doerr]

On Fri, 12 Sep 2025 00:23:04 GMT, Dean Long <dlong at openjdk.org> wrote:

>> That would require much more changes. The barrier sequence is expected to have a fixed size.
>
> OK, then how about we align the beginning using
> ` __ align(4, offset() + 3*6 + 2);`
> to make it more self-documenting?

Or better: define a constant for 3*6 + 2 and reuse it in `class NativeMethodBarrier`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27213#discussion_r2343425223