RFR: 7904089: jextract cannot handle "void foo(int foo)"

[Nizar Benalla]

Please review this change to fix a name conflicts between functions and name parameters.

TIA!

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Commit messages:
 - handle name conflicts

Changes: https://git.openjdk.org/jextract/pull/292/files
  Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=292&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7904089
  Stats: 117 lines in 4 files changed: 116 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jextract/pull/292.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/292/head:pull/292

PR: https://git.openjdk.org/jextract/pull/292