RFR: 8336938: Update libFFI to 3.4.6

[Kevin Rushforth]

On Wed, 7 Aug 2024 00:26:13 GMT, Alexander Matveev <almatvee at openjdk.org> wrote:

> - libFFI updated to 3.4.6.
> - No additional changes are done.
> - Tested on Windows, macOS and Linux with all supported formats.

@tiainen Do you want to be the second reviewer?

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PR Comment: https://git.openjdk.org/jfx/pull/1531#issuecomment-2285031562