Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/244ad31..39cffda

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

Change-Id: I92a7ae51de2eec216a072bfa80413dd5db556948
Reviewed-on: https://chromium-review.googlesource.com/1074560
Commit-Queue: v8 autoroll <v8-autoroll@chromium.org>
Reviewed-by: v8 autoroll <v8-autoroll@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53379}

DEPS

@@ -12,7 +12,7 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '244ad31ca7152077ea5d812da20e7b35fd64e68b',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '39cffdabab587544c4bb01f3618ea3f7ae65a889',
   'v8/tools/gyp':
     Var('chromium_url') + '/external/gyp.git' + '@' + 'd61a9397e668fa9843c4aa7da9e79460fe590bfb',
   'v8/third_party/depot_tools':