RFR: 8334137: Marlin: replace sun.misc.Unsafe memory access methods with FFM [v8]

[Kevin Rushforth]

On Wed, 11 Jun 2025 18:39:25 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> it's a minor thing;  we could do it later if you plan a follow-up - I more dislike the idea of having an unused array...
>
> I'll file a few cleanup bugs before I integrate and note them in comments.

I decided to fix the constructor now (simple cleanup without any behavior change).

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PR Review Comment: https://git.openjdk.org/jfx/pull/1814#discussion_r2140935874