compiler_wrapper: add missing unused-but-set-var

This CL adds a Wno-unused-but-set-var flag that was accidentally missing
in a clangPostFlags field. THis is already present in the llvm repo,
must have been fixed in there without mirroring it.

BUG=b:195433889
TEST=None

Change-Id: I23fcc91aee7b316cd70652f0119177d5ebdf7bbd
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3319338
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Commit-Queue: Ryan Beltran <ryanbeltran@chromium.org>
Tested-by: Ryan Beltran <ryanbeltran@chromium.org>
10 files changed