[foreign-memaccess+abi] RFR: Micro optimizations and tidy [v2]

[Paul Sandoz]

On Fri, 19 Aug 2022 08:57:09 GMT, Per Minborg <duke at openjdk.org> wrote:

>> This small PR adds some optimizations and tidies up some imports.
>
> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update after comments

Marked as reviewed by psandoz (Committer).

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PR: https://git.openjdk.org/panama-foreign/pull/708