RFR: Update jextract 21 with latest fixes

Wed Nov 22 10:30:38 UTC 2023

On Mon, 20 Nov 2023 18:29:19 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This PR brings three changesets to the `master` branch, so that we can release updated binaries:
> 
> * https://git.openjdk.org/jextract/pull/132
> * https://git.openjdk.org/jextract/pull/131
> * https://github.com/openjdk/jextract/pull/137

Marked as reviewed by jvernee (Committer).

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PR Review: https://git.openjdk.org/jextract/pull/139#pullrequestreview-1744054288