[crac] RFR: 8373781: [CRaC] Permit -XX:CPUFeatures on other platforms

[Radim Vansa]

On Wed, 17 Dec 2025 10:26:55 GMT, Radim Vansa <rvansa at openjdk.org> wrote:

> Currently `-XX:CPUFeatures` option is available only on `x86_64`. This complicates creating multiarch container images that are meant to be universally runnable (with `-XX:CPUFeatures=generic`).
> 
> I propose to make this option available on all architectures, with the non-arch specific values:
> * `generic`
> * `native`
> * `ignore`
> 
> The implementation on non-x86_64 will only validate the sanity of the value.
> 
> The related option `-XX:+ShowCPUFeatures` will print an informative message (saying that the option does not make much sense).
> 
> `-XX:+IgnoreCPUFeatures` will be permitted as well, but it will be a no-op on the other architectures.

I've replaced the shell-based CPUFeatures test, and added test cases.

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PR Comment: https://git.openjdk.org/crac/pull/282#issuecomment-3687086644