RFR: 7903384: sync jextract for jdk 20 panama API changes

Mon Dec 5 16:19:35 UTC 2022

Synching jextract with jdk 20 Panama API changes JEP 434: Foreign Function & Memory API (Second Preview)

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Commit messages:
 - default case cannot be used error in CDeclarationPrinter.java. Fixed comment in libzstd sample's README.md
 - avoid ExitException. Use ArenaCleanup to do cleanup just before confined Arena is closed.
 - 7903384: sync jextract for jdk 20 panama API changes

Changes: https://git.openjdk.org/jextract/pull/94/files
 Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=94&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903384
  Stats: 5240 lines in 78 files changed: 3391 ins; 43 del; 1806 mod
  Patch: https://git.openjdk.org/jextract/pull/94.diff
  Fetch: git fetch https://git.openjdk.org/jextract pull/94/head:pull/94

PR: https://git.openjdk.org/jextract/pull/94