[all-commits] [llvm/llvm-project] ced0f2: Improve clang-format-diff help output (#73491)

[serge-sans-paille via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ced0f28a35b8a14759e6bd9418e8c8a7c35775c8
      https://github.com/llvm/llvm-project/commit/ced0f28a35b8a14759e6bd9418e8c8a7c35775c8
  Author: serge-sans-paille <sguelton at mozilla.com>
  Date:   2023-11-28 (Tue, 28 Nov 2023)

  Changed paths:
    M clang/tools/clang-format/clang-format-diff.py

  Log Message:
  -----------
  Improve clang-format-diff help output (#73491)

It is quite common to symlink clang-format-diff.py to clang-format-diff,
and in that case the help output still refers to the .py version.
Compute it instead to work in both setup.