wrapper: add support for Tricium clang-tidy

This adds a special `WITH_TIDY` mode that's specifically for use with
Tricium. Crucially, this has us dump diagnostics as YAML, and stash a
fair amount of information about each clang-tidy invocation in the same
place where we dump YAML.

These bits are intended to be used by the script added in
I54ecc88d38faa4bfd502d632d3fd5c74734dabc0.

BUG=chromium:1035951
TEST=Ran on all platform2 packages `emerge`able on amd64-generic.

Change-Id: I63ef06dc6ddc016ebb6ba0c4a0cea8320fef7415
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2245785
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
5 files changed