[gn] Port exec_script whitelist from chromium/src/build

.gn

Index: .gn
diff --git a/.gn b/.gn
index e80fc3a76922a5b085cab8c202fc1c4fe3d1259a..da056aa93664c2baa1c0bf6f12a0da54e69161f3 100644
--- a/.gn
+++ b/.gn
@@ -29,14 +29,22 @@ exec_script_whitelist = [
   "//build/config/compiler/BUILD.gn",
   "//build/config/gcc/gcc_version.gni",
   "//build/config/ios/ios_sdk.gni",
+  "//build/config/linux/atk/BUILD.gn",
   "//build/config/linux/BUILD.gn",
   "//build/config/linux/pkg_config.gni",
   "//build/config/mac/mac_sdk.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/nacl/BUILD.gn",
   "//build/toolchain/win/BUILD.gn",
+  "//build/util/branding.gni",
+  "//build/util/version.gni",
   "//test/test262/BUILD.gn",
 ]