Rolling v8/build/gyp to 121d89dfcd4f6ebe1c89524b3f9ca11ddd437e77

Rolling v8/tools/clang to a09a5fee59be457e0d7213d86f8bac72d232860d

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

Review URL: https://codereview.chromium.org/1322933004

Cr-Commit-Position: refs/heads/master@{#30530}