[foreign-jextract] Integrated: 8261073: Remove @C annotations from jextracted code

[Athijegannathan Sundararajan]

removing C type annotations in generated code

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Commit messages:
 - 8261073: Remove @C annotations from jextracted code

Changes: https://git.openjdk.java.net/panama-foreign/pull/447/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=447&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261073
  Stats: 388 lines in 13 files changed: 0 ins; 328 del; 60 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/447.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/447/head:pull/447

PR: https://git.openjdk.java.net/panama-foreign/pull/447