GitLab

A follow-up for https://chromium-review.googlesource.com/c/chromium/src/+/1112199.
These two changes should significantly speed up code coverage builds. Build time,
binary sizes and runtime all get improved by ~2x. See the other CL description and
the bugs referenced for more precise numbers and targets tested.

We already have an assertion against enabling both use_sanitizer_coverage and
use_clang_coverage via GN args, but the former still could be turned on indirectly
if a fuzzing engine is used (e.g. use_libfuzzer or use_afl).

Bug: 846054
Change-Id: Idcd87a4589eda71e519d382ef235b38cc0984ed3
Reviewed-on: https://chromium-review.googlesource.com/1112305Reviewed-by: Abhishek Arya <inferno@chromium.org>
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569779}