RFR: 8339527: Adjust threshold for MemorySegment::fill native invocation

[Jorn Vernee]

On Tue, 8 Apr 2025 13:37:44 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> This PR proposes to increase the threshold for `MemorySegment::fill` operations on AArch-64 platforms.
> 
> Performance looks good:
> 
> ![image](https://github.com/user-attachments/assets/56a83541-cb84-4a37-a914-fdddfde343c6)
> 
> ![image](https://github.com/user-attachments/assets/ff2c33e0-b300-482d-b93e-217a11e07202)

Marked as reviewed by jvernee (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/24510#pullrequestreview-2750396029