Work on Mac GN build

build/toolchain/clang.gni

 # Copyright (c) 2013 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.
 
 declare_args() {
   # Enable the optional type profiler in Clang, which will tag heap allocations
   # with the allocation type.
   use_clang_type_profiler = false
 }
-
-if (is_clang) {
-  # Define "make_clang_dir" which is the directory relative to the source root
-  # of the clang directory we're using. This is used for defining the header
-  # for GYP so it must match the directory format of GYP (rather than using
-  # GN-style "//..." paths).
-  if (is_linux && use_clang_type_profiler) {
-    if (cpu_arch == "x64") {
-      make_clang_dir = "third_party/llvm-allocated-type/Linux_x64"
-    } else {
-      # 32-bit Clang is unsupported. It may not build. Put your 32-bit Clang in
-      # this directory at your own risk if needed for some purpose (e.g. to
-      # compare 32-bit and 64-bit behavior like memory usage). Any failure by
-      # this compiler should not close the tree.
-      make_clang_dir = "third_party/llvm-allocated-type/Linux_ia32"
-    }
-  } else {
-    make_clang_dir = "third_party/llvm-build/Release+Asserts"
-  }
-
-  # This includes the array values but not the 'make_global_settings' name.
-  make_clang_global_settings =
-    "['CC', '$make_clang_dir/bin/clang']," +
-    "['CXX', '$make_clang_dir/bin/clang++']," +
-    "['CC.host', '\$(CC)']," +
-    "['CXX.host', '\$(CXX)'],"
-}