Update V8 DEPS.

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/e1167bf..7d6c957

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

Change-Id: I135164556a3821e81177cae1cb6e3fadc1cac0ea
Reviewed-on: https://chromium-review.googlesource.com/1163290Reviewed-by: V8 Autoroller <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: V8 Autoroller <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#54907}

DEPS

@@ -13,7 +13,7 @@ vars = {
 
 deps = {
   'v8/build':
-    Var('chromium_url') + '/chromium/src/build.git' + '@' + 'e1167bfd0a335b9f195cbd76164630098c0f0577',
+    Var('chromium_url') + '/chromium/src/build.git' + '@' + '7d6c95721fddb6d1496b7020efe8b1b678aeded3',
   'v8/tools/gyp':
     Var('chromium_url') + '/external/gyp.git' + '@' + 'd61a9397e668fa9843c4aa7da9e79460fe590bfb',
   'v8/third_party/depot_tools':