[clang] [git-clang-format] Fix: make the tool backward compatible (PR #108721)

[Eden Reich via cfe-commits]

edenreich wrote:

Because I was trying to use this tool with the current stable release of clang-format, and it's currently broken?

IDK, or I just wait for the next release of clang-format before I can consider using git-clang-format 🤷‍♂️

https://github.com/llvm/llvm-project/pull/108721