Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/6613a83..a4ee526

TBR=machenbach@chromium.org,tmrts@chromium.org

Change-Id: I7b2ff3c4afa602b7d5ab13ea93dac9f8bb1d63df
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1917057Reviewed-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@{#64993}

DEPS

@@ -79,7 +79,7 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '6613a8384bc789e8a3867023c139f9b79dd25ce7',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'a4ee526e3c5a993724bffc381abe4d03f8c4f5ec',
   'v8/third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + '1f392b83a83a069eac0b71679b19fedf7958ec4d',
   'v8/third_party/icu':