Update V8 DEPS.

Rolling v8/tools/clang: https://chromium.googlesource.com/chromium/src/tools/clang/+log/f2ca3e0..509676b

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

Change-Id: I5d6e78e23d83234c8c80eaef4a7c8a51c7575e6a
Reviewed-on: https://chromium-review.googlesource.com/777929Reviewed-by: v8 autoroll <v8-autoroll@chromium.org>
Commit-Queue: v8 autoroll <v8-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49467}

DEPS

@@ -51,7 +51,7 @@ deps = {
   'v8/test/test262/harness':
     Var('chromium_url') + '/external/github.com/test262-utils/test262-harness-py.git' + '@' + '0f2acdd882c84cff43b9d60df7574a1901e2cdcd',
   'v8/tools/clang':
-    Var('chromium_url') + '/chromium/src/tools/clang.git' + '@' + 'f2ca3e05e48b1bf8343fb270dc086e39c6e6017c',
+    Var('chromium_url') + '/chromium/src/tools/clang.git' + '@' + '509676b083e667c899921051dbb7ed87721698b0',
   'v8/tools/luci-go':
     Var('chromium_url') + '/chromium/src/tools/luci-go.git' + '@' + '45a8a51fda92e123619a69e7644d9c64a320b0c1',
   'v8/test/wasm-js':