gn: Remove unnecessary v8 defaults

chrome/installer/mini_installer/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/compiler/compiler.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/config/win/visual_studio_version.gni")
-import("//build_overrides/v8.gni")
 import("//chrome/test/mini_installer/mini_installer_test.gni")
 import("//chrome/version.gni")
 import("//third_party/icu/config.gni")
 import("//ui/base/ui_features.gni")
+import("//v8/gni/v8.gni")
 
 config("mini_installer_compiler_flags") {
   # Disable buffer security checking.
   cflags = [ "/GS-" ]
 }
 
 source_set("lib") {
   sources = [
     "appid.h",
     "chrome.release",
@@ skipping 262 matching lines @@
     args = [
       "--out",
       "$target_name.exe",
     ]
     deps = [
       ":mini_installer",
       "//chrome/installer/test:alternate_version_generator",
     ]
   }
 }