Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/fe88ff7..8373abc

TBR=machenbach@chromium.org,hablich@chromium.org,sergiyb@chromium.org

Change-Id: Ib2f4e3846ba51a5ed9d07005ad9d3f8fb0604c74
Reviewed-on: https://chromium-review.googlesource.com/c/1356910Reviewed-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@{#57987}

DEPS

@@ -13,7 +13,7 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'fe88ff746376d6b71395d7d536644da95c53e3c9',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '8373abc66edfc19ac0d3b1ad146a3ed3c5eb748e',
   'v8/third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + '61ea30737c65fb3a6ad7096f447465e58f8b915c',
   'v8/third_party/icu':