Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/3110f72..18a5f87

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

Change-Id: I0d602535bf0e696d5a96bacdf2a8a74774a7a0ed
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2467117Reviewed-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@{#70464}

DEPS

@@ -82,7 +82,7 @@ vars = {
 
 deps = {
   'build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '3110f72ad5d9e95048f2e1144a50d3697a941e85',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '18a5f878bf0ed08bb75cee422976fe9851c03794',
   'third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + 'b073999c6f90103a36a923e63ae8cf7a5c9c6c8c',
   'third_party/icu':