Abel Briggs

FWIW, `pyperf system tune` does not support Windows (understandably so - automatic system tuning is logistically difficult on Windows), so an opt-out of some sort for tuning on `pyperformance run`...

> @abbriggs my commit name caused github to automatically close this. Can you please try the latest scripts and verify that it is solved for you? Both problems discussed in...

> @abbriggs Sorry for the delay - this was reproduced and should now be fixed by applying `abspath` to `source_dir` (not to each individual `DebugLoc.File`). Please say if this fixes...

I've been testing with this PR's patches on a fairly large project built with `clang-cl`, and it appears to be working without too much issue. I did need to add...