llvm_tools: add revision autodetection to the patch cleanup script

This is the last bit of b/332589934#comment3. Once this lands & is
tested, we can add a tiny script to work in a cros worktree, add that to
cron, and consider this fixed.

BUG=b:332589934
TEST=Ran on Chrotomation

Change-Id: I812f9e75e2349b88308be89687687131159bafc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/5435855
Commit-Queue: George Burgess <gbiv@chromium.org>
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Tested-by: George Burgess <gbiv@chromium.org>
2 files changed