I got tired of waiting for it to run, so I added some of the "worker" queue code that I wrote for the assets-for-api-docs generator.
I also tried out putting all the files in one call to clang-tidy with the -p argument, but that was still a lot slower because it runs them all on one core. This runs separate jobs for each file, simultaneously, and then reports the results at the end (associated with each file, of course).
