RFR: 7903285: jextract should skip static symbols

[Athijegannathan Sundararajan]

Cursor linkage kind CXLinkage_Internal is used for static variables and static functions. Filtering the cursors with that linkage kind. Most of the changes are due to regenerated clang bindings to include clang_getCursorLinkage and CXLinkageKind enum constants.

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Commit messages:
 - 7903285: jextract should skip static symbols

Changes: https://git.openjdk.org/jextract/pull/70/files
 Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=70&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903285
  Stats: 484 lines in 26 files changed: 309 ins; 144 del; 31 mod
  Patch: https://git.openjdk.org/jextract/pull/70.diff
  Fetch: git fetch https://git.openjdk.org/jextract pull/70/head:pull/70

PR: https://git.openjdk.org/jextract/pull/70