[Mac/GN] Add a new linker_driver.py option to save unstripped linker output.

build/config/BUILDCONFIG.gn

 # 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.
 
 # =============================================================================
 # PLATFORM SELECTION
 # =============================================================================
 #
 # There are two main things to set: "os" and "cpu". The "toolchain" is the name
 # of the GN thing that encodes combinations of these things.
@@ skipping 511 matching lines @@
   # Many targets remove these configs, so they are not contained within
   # //build/config:executable_config for easy removal.
   _linker_configs = [
     "//build/config/win:default_incremental_linking",
 
     # Default to console-mode apps. Most of our targets are tests and such
     # that shouldn't use the windows subsystem.
     "//build/config/win:console",
   ]
 } else if (is_mac) {
-  _linker_configs = [ "//build/config/mac:strip_all" ]
+  _linker_configs = [
+    "//build/config/mac:strip_all",
+    "//build/config/mac:save_unstripped_output",
+  ]
 } else {
   _linker_configs = []
 }
 
 # Executable defaults.
 default_executable_configs = default_compiler_configs + [
                                "//build/config:default_libs",
                                "//build/config:executable_config",
                              ] + _linker_configs
 set_defaults("executable") {
@@ skipping 87 matching lines @@
 set_defaults("component") {
   if (is_component_build) {
     configs = default_shared_library_configs
     if (is_android) {
       configs -= [ "//build/config/android:hide_native_jni_exports" ]
     }
   } else {
     configs = default_compiler_configs
   }
 }