[jfx23u] RFR: 8336938: Update libFFI to 3.4.6

[Alexander Matveev]

- Clean backport of JDK-8336938.

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Commit messages:
 - Backport f1bac5a829e1f2b75b863c4f0822bf418107a1fb

Changes: https://git.openjdk.org/jfx23u/pull/11/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx23u&pr=11&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336938
  Stats: 1056 lines in 26 files changed: 388 ins; 373 del; 295 mod
  Patch: https://git.openjdk.org/jfx23u/pull/11.diff
  Fetch: git fetch https://git.openjdk.org/jfx23u.git pull/11/head:pull/11

PR: https://git.openjdk.org/jfx23u/pull/11