Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/3d38a62..ffd4756

TBR=machenbach@chromium.org,tmrts@chromium.org,v8-waterfall-sheriff@grotations.appspotmail.com

Change-Id: I2692889cddf15d7d9adfbe9594bd94fa41aea87c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2604592Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#71881}

DEPS

@@ -88,7 +88,7 @@ vars = {
 
 deps = {
   'build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '3d38a62e5a0deab4366b1e55e0f9abf9a3a2d945',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'ffd4756efa45cc94ba27cb896badb29444c8c641',
   'third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + '46ef281c525f704bb9445142e9e4d70dacae7d4d',
   'third_party/icu':