llvm_tools: add a nightly clang-tidy diagnostic checker

This CL adds a tool that files bugs on us to evaluate new clang-tidy
checks as they're landed upstream. The intent is for this to be run at
some regular interval. Hopefully it can be extended to clang, too?

BUG=None
TEST=Ran a few times on my machine with the bug bits stubbed out

Change-Id: I1736d6e18009bb4ea9ba0a9b4d068ed0331d3353
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3539313
Reviewed-by: Christopher Di Bella <cjdb@google.com>
Commit-Queue: Christopher Di Bella <cjdb@google.com>
Tested-by: George Burgess <gbiv@chromium.org>
2 files changed