[jdk21] RFR: 8309937: Add @sealedGraph for some Panama FFM interfaces

[Per Minborg]

On Mon, 19 Jun 2023 14:58:13 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> Hi all,
> 
> This pull request contains a backport of commit [b412fc79](https://github.com/openjdk/jdk/commit/b412fc79c3c2548df10918090beedaf6b2d08d96) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
> 
> The commit being backported was authored by Per Minborg on 16 Jun 2023 and was reviewed by Maurizio Cimadamore.
> 
> Thanks!

Yes. I recently added it. Please review.

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PR Comment: https://git.openjdk.org/jdk21/pull/34#issuecomment-1600323874