[sanitizers] Using correct dynamic linking option on mac.

build/config/sanitizers/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 # Contains the dependencies needed for sanitizers to link into executables and
 # shared_libraries. Unconditionally depend upon this target as it is empty if
@@ skipping 15 matching lines @@
     if (use_prebuilt_instrumented_libraries) {
       deps += [ "//third_party/instrumented_libraries:deps" ]
     }
     if (use_custom_libcxx) {
       deps += [ "//buildtools/third_party/libc++:libcxx_proxy" ]
     }
   }
 }
 
 config("sanitizer_options_link_helper") {
-  if (!is_win) {
+  if (is_mac) {
+    ldflags = [ "-Wl,-U,_sanitizer_options_link_helper" ]
+  } else if (!is_win) {
     ldflags = [ "-Wl,-u_sanitizer_options_link_helper" ]
   }
 }
 
 source_set("options_sources") {
   visibility = [
     ":deps",
     "//:gn_visibility",
   ]
   sources = [
@@ skipping 259 matching lines @@
     if (target_cpu == "arm") {
       # http://crbug.com/517105
       cflags += [
         "-mllvm",
         "-sanitizer-coverage-block-threshold=0",
       ]
     }
     defines = [ "SANITIZER_COVERAGE" ]
   }
 }