llvm_tools: add logging to the revert checker

Somehow this revert checker is dropping reverts on the floor, which is
confusing to me. Log the 'last run' state so it's easier to understand
what this checker was thinking.

BUG=None
TEST=Ran the script

Change-Id: I586bbbd35f7d414faebda9068c04f552152891de
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2180842
Tested-by: George Burgess <gbiv@chromium.org>
Reviewed-by: Tiancong Wang <tcwang@google.com>
1 file changed