RFR: Layout updates [v2]

[Athijegannathan Sundararajan]

On Mon, 29 Aug 2022 09:19:54 GMT, Per Minborg <duke at openjdk.org> wrote:

>> This PR updates jextract to work with the recent changes in Panama.
>
> Per Minborg has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Fix javadoc
>  - Update after comments

LGTM

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Marked as reviewed by sundar (Committer).

PR: https://git.openjdk.org/jextract/pull/62