Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/83e2334..b7fc8c9

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

Change-Id: I9cde52ff7a44cc90f129fc393fa3f24bd7277d1f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2576617Reviewed-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@{#71631}

DEPS

@@ -88,7 +88,7 @@ vars = {
 
 deps = {
   'build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '83e2334ab82b5909cb97bc1a78098b0a2e7487b3',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'b7fc8c9ce54300725a1bf6a86bf88b97029f6630',
   'third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + 'e602c60a2b59e4a74033fe7580e50d9de9f5753e',
   'third_party/icu':