Rolling v8/buildtools to 5378d73123b64907773cc5c1bb027b2f765ff00a

Rolling v8/tools/clang to 41bff4c5ba97022c0fe69a59d8892a6c45fb0867

TBR=machenbach@chromium.org,vogelheim@chromium.org,hablich@chromium.org

Review URL: https://codereview.chromium.org/1889043002

Cr-Commit-Position: refs/heads/master@{#35505}