Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/34b1290..4250046

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

Change-Id: I774107b9e6408832b63d9171e26a3dfbf6231f79
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1857432Reviewed-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@{#64266}

DEPS

@@ -71,7 +71,7 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '34b12904d8e4897909b6172f7a4bea22f5b6cf19',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '42500462ec57678669e2d103838d87b19f04290f',
   'v8/third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + '5abb9b7c5d0c0a5f81f4a0da741680df9b9d128c',
   'v8/third_party/icu':