rustfmt-nightly: add -headerpad_max_install_names x64 darwin
fix failing install_name_tool not having enough space to write the path
into the binary
> error: install_name_tool: changing install names or rpaths can't be redone for: /nix/store/.../git-rustfmt (for architecture x86_64) because larger updated load commands do not fit (the program must be relinked, and you may need to use -headerpad or -headerpad_max_install_names)
