Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/248dc44..603888a

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

Change-Id: Ifcf2c63935b397062ad5a757e277d15fb8dfbb5a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2524643Reviewed-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@{#71023}

DEPS

@@ -91,7 +91,7 @@ vars = {
 
 deps = {
   'build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + '248dc445602280f6dbae2d440cdb487da3cd1258',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '603888af0278b1e15c8b10eb76a94318046ae559',
   'third_party/depot_tools':
     Var('chromium_url') + '/chromium/tools/depot_tools.git' + '@' + 'b674f8a27725216bd2201652636649d83064ca4a',
   'third_party/icu':