Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/be4bea4..d6803e2

TBR=v8-waterfall-sheriff@grotations.appspotmail.com

Change-Id: If28b7b4a648236a6c0509d54d8b9577244810777
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2710770Reviewed-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@{#72885}

DEPS

@@ -88,7 +88,7 @@ vars = {
 
 deps = {
   'build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'be4bea4bee02c20f3856ebe0ec67de824bbfd2fe',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'd6803e2773f7ecf64dc908afc6626531a2eb72ed',
   'third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + '011cc41c3d07b1577de9e794adfb73591223a995',
   'third_party/icu':