RFR: 8334137: Marlin: replace sun.misc.Unsafe memory access methods with FFM [v7]

[Kevin Rushforth]

On Wed, 11 Jun 2025 15:17:59 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> modules/javafx.graphics/src/main/java/com/sun/marlin/MaskMarlinAlphaConsumer.java line 111:
>> 
>>> 109:         byte[] _ALPHA_MAP = buildAlphaMap(MarlinConst.MAX_AA_ALPHA);
>>> 110:         ALPHA_MAP = _ALPHA_MAP; // Keep alive the OffHeapArray
>>> 111:         ALPHA_MAP_OFF_HEAP = new OffHeapArray(ALPHA_MAP, ALPHA_MAP.length); // 1K
>> 
>> L110: is `ALPHA_MAP` needed to keep the `parent` reference in `OffHeapArray`?  if so, why not use a single `Object` instead of an array?
>
> It's actually unused (in practice), but I didn't want to change the logic any more than I had to. It doesn't matter enough to care about, so I didn't want to think about whether the reference could be eliminated.

[JDK-8359260](https://bugs.openjdk.org/browse/JDK-8359260)

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PR Review Comment: https://git.openjdk.org/jfx/pull/1814#discussion_r2140976467