Use //build/dotfile_settings.gni to reduce blocked auto-rolls

.gn

Index: .gn
diff --git a/.gn b/.gn
index 5da4f241b56775c1df372067b3f46bbaefa84f13..792516567a538ddf1d57c7feeb1e291cec88a423 100644
--- a/.gn
+++ b/.gn
@@ -6,6 +6,8 @@
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
+import("//build/dotfile_settings.gni")
+
 # The location of the build configuration file.
 buildconfig = "//build/config/BUILDCONFIG.gn"
 
@@ -43,32 +45,9 @@ check_targets = [
 # These are the list of GN files that run exec_script. This whitelist exists
 # to force additional review for new uses of exec_script, which is strongly
 # discouraged except for gypi_to_gn calls.
-exec_script_whitelist = [
-  "//build/config/BUILD.gn",
-  "//build/config/android/BUILD.gn",
-  "//build/config/android/config.gni",
-  "//build/config/android/internal_rules.gni",
-  "//build/config/android/rules.gni",
-  "//build/config/compiler/BUILD.gn",
-  "//build/config/gcc/gcc_version.gni",
-  "//build/config/ios/ios_sdk.gni",
-  "//build/config/linux/BUILD.gn",
-  "//build/config/linux/pkg_config.gni",
-  "//build/config/mac/mac_sdk.gni",
-  "//build/config/mac/rules.gni",
-  "//build/config/posix/BUILD.gn",
-  "//build/config/sysroot.gni",
-  "//build/config/win/BUILD.gn",
-  "//build/config/win/visual_studio_version.gni",
-  "//build/gn_helpers.py",
-  "//build/gypi_to_gn.py",
-  "//build/toolchain/concurrent_links.gni",
-  "//build/toolchain/gcc_toolchain.gni",
-  "//build/toolchain/mac/BUILD.gn",
-  "//build/toolchain/toolchain.gni",
-  "//build/toolchain/win/BUILD.gn",
-  "//third_party/boringssl/BUILD.gn",
-  "//third_party/openh264/BUILD.gn",
-  "//third_party/opus/BUILD.gn",
-  "//webrtc/modules/video_render/BUILD.gn",
-]
+exec_script_whitelist = build_dotfile_settings.exec_script_whitelist + [
+                          "//third_party/boringssl/BUILD.gn",
+                          "//third_party/openh264/BUILD.gn",
+                          "//third_party/opus/BUILD.gn",
+                          "//webrtc/modules/video_render/BUILD.gn",
+                        ]