clang build script: run check-all during bootstrap on mac

Seems like libc++ tests pass on LUCI now.

Bug: 731375
Change-Id: I1e0236338c881f8c1006d77203b6e3119fcae04e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2687656
Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Auto-Submit: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#852778}
GitOrigin-RevId: 8711cbb8857cbcce28d90121d7987bb75654d3ca
1 file changed