Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/6d17aae..3e739fd

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

Change-Id: Ibb3a878d44b3fd56e95bbfa608500761c882bd21
Reviewed-on: https://chromium-review.googlesource.com/444426Reviewed-by: v8 autoroll <v8-autoroll@chromium.org>
Commit-Queue: v8 autoroll <v8-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43301}

DEPS

@@ -8,7 +8,7 @@ vars = {
 
 deps = {
   "v8/build":
-    Var("chromium_url") + "/chromium/src/build.git" + "@" + "6d17aaeb072c7e5f8645e7b2aca1669efd8eb81d",
+    Var("chromium_url") + "/chromium/src/build.git" + "@" + "3e739fd08b3eb4f63d2039f5d3d9908f8c827491",
   "v8/tools/gyp":
     Var("chromium_url") + "/external/gyp.git" + "@" + "e7079f0e0e14108ab0dba58728ff219637458563",
   "v8/third_party/icu":