compiler_wrapper: add -clang-tidy-flag support

This CL adds support for specifying compiler flags that're meant to be
passed only to clang-tidy. This allows for easier local experimentation
with clang-tidy by users.

BUG=chromium:982944
TEST=`WITH_TIDY=1 emerge-amd64-generic biod` with custom cflags; cq+1
     on crrev.com/c/2308774

Change-Id: I654559d14a78ade4920fe37757fb5b249a997290
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2309152
Reviewed-by: Caroline Tice <cmtice@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
3 files changed