clang-extra-tools: git-clang-format expects "python" binary to exist

The git-clang-format script provided by clang-extra tools has the shebang #!/usr/bin/env python which fails on alpine edge because there is no python binary (only python3). Requiring the workaround of symlinking python3 to python.

I had a look around the llvm infra and couldn't find a good place to report this issue there, please redirect me if applicable.