Run clang-format in 8 threads

[ShabbyX]

For faster runs of ./util/clang_format_all.sh

[baldurk]

I'm going to decline this because it looks like -P is not a standard xargs parameter so I don't know how portable this is. Normally it would be good enough, but since clang_format_all.sh should be rarely run I don't think this is worth making it potentially break somewhere.

Anyone who's developing regularly for RenderDoc should either have IDE integration format files, or use something like git clang-format to format only modified files. This brute force format of the whole repo is only used either for CI to check formatting or for someone who maybe doesn't care to properly set up clang-format at all. A minute to run the script in that case is not the end of the world.

[ShabbyX]

Ah interesting, didn't know about git clang-format. Thank you, that works.