Rolling v8/buildtools to 11961c21510b90aa6057064459a1af53f3fff449

Rolling v8/tools/clang to 55e0efc650db1b2c60b50c8c32cfc8a27d8f2986

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

Review URL: https://codereview.chromium.org/1641473002

Cr-Commit-Position: refs/heads/master@{#33532}