Rolling v8/buildtools to fa660d47fa1a6c649d5c29e001348447c55709e6

Rolling v8/tools/clang to fbd2e50b735151d7745bca153f7f17ea896dcfb7

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/1158313003

Cr-Commit-Position: refs/heads/master@{#28705}