Update GN files w/ changes needed to make sanitizers work.

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 493 matching lines @@
   _windows_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",
   ]
 }
 
 # Executable defaults.
-_executable_configs = _native_compiler_configs + [
-                        "//build/config:default_libs",
-                        "//build/config:executable_config",
-                      ]
+_executable_configs =
+    _native_compiler_configs + [
+      "//build/config:default_libs",
+      "//build/config:executable_config",
+
+      # If we're using the prebuilt instrumented libraries with the
+      # sanitizers, we need to add ldflags to every binary to make sure
+      # they are picked up. We can't check for using_sanitizer in BUILDCONFIG,
+      # so we add the config unconditionally and have it be empty when not
+      # using the libraries.
+      "//third_party/instrumented_libraries:prebuilt_instrumented_libraries_ldflags",
+    ]
 if (is_win) {
   _executable_configs += _windows_linker_configs
 }
+
 set_defaults("executable") {
   configs = _executable_configs
 }
 
 # Static library defaults.
 set_defaults("static_library") {
   configs = _native_compiler_configs
 }
 
 # Shared library and loadable module defaults (also for components in component
 # mode).
-_shared_library_configs = _native_compiler_configs + [
-                            "//build/config:default_libs",
-                            "//build/config:shared_library_config",
-                          ]
+_shared_library_configs =
+    _native_compiler_configs + [
+      "//build/config:default_libs",
+      "//build/config:shared_library_config",
+      "//third_party/instrumented_libraries:prebuilt_link_helper",
+    ]
 if (is_win) {
   _shared_library_configs += _windows_linker_configs
 } else if (is_android) {
   # Strip native JNI exports from shared libraries by default. Binaries that
   # want this can remove this config.
   _shared_library_configs +=
       [ "//build/config/android:hide_native_jni_exports" ]
 }
 set_defaults("shared_library") {
   configs = _shared_library_configs
@@ skipping 74 matching lines @@
     forward_variables_from(invoker, "*", [ "visibility" ])
 
     # All shared libraries must have the sanitizer deps to properly link in
     # asan mode (this target will be empty in other cases).
     if (!defined(deps)) {
       deps = []
     }
     deps += [ "//build/config/sanitizers:deps" ]
   }
 }