Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/68fec68..6ae4be1

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

Change-Id: Iedfb1d8a959bfa8a52939d7b3617bafdf4043051
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2598675Reviewed-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@{#71842}

DEPS

@@ -88,7 +88,7 @@ vars = {
 
 deps = {
   'build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '68fec68de71c92c09b2755742b9b4bf9e5b975bf',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '6ae4be1ce52a03f157d113fb7c8b437ca38a015d',
   'third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + '67e12286df04ef0eeec3aeaf6f224d2fe11751b7',
   'third_party/icu':