Rolling v8/build to 76d9f8b4fcae07fb82f28295468cf92bade935bd

Rolling v8/buildtools to db6179b29f90d28026b0cb23ef71d56ec31b8bd6

Rolling v8/tools/clang to 775e2f874b9f53f0e82c4e7c61dc29f3cdcb3379

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

Review-Url: https://codereview.chromium.org/2117993002
Cr-Commit-Position: refs/heads/master@{#37486}