[foreign-memaccess+abi] RFR: 8301801: Implement arena-centric API [v2]

[Maurizio Cimadamore]

On Thu, 9 Feb 2023 18:46:47 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Okay, it looks like for in memory return on e.g. SysV, we are using just a plain `C_POINTER` layout without a pointee layout attached, so the boxed address should already have unbounded size.
>
> I guess we could also potentially attach the right size to the address layout, to make this buffer copy just a bit more safe. But, we can do that later.

This is no longer needed - it was required when I made the linker more strict to use zero-length memory segments, but this is no longer the case. Will revert.

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PR: https://git.openjdk.org/panama-foreign/pull/781