Update V8 DEPS.
Update V8 DEPS.

Rolling v8/tools/clang to 1efaf64b8e648c8c6539245b10cbea6f3004eb61

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/1168033003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#28820}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh