[foreign-jextract] RFR: 8275111: update libclang bindings after recent jextract changes

[Athijegannathan Sundararajan]

regenerated jextract. generating CXString struct

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Commit messages:
 - 8275111: update libclang bindings after recent jextract changes

Changes: https://git.openjdk.java.net/panama-foreign/pull/598/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=598&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275111
  Stats: 241 lines in 10 files changed: 230 ins; 8 del; 3 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/598.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/598/head:pull/598

PR: https://git.openjdk.java.net/panama-foreign/pull/598