Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/66bcca0..2b40e7b

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

Change-Id: Ice498a61cfe92db159bb1252c027110c783e8ff2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1880337Reviewed-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@{#64574}

DEPS

@@ -71,7 +71,7 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '66bcca0260b1a61cb0a88f7a2275e043b325a21b',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '2b40e7bc8bf3e5c0d64c1f2f41bca519c11336df',
   'v8/third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + 'ebba8d75bf65250198a1f5c84295e119129915bd',
   'v8/third_party/icu':