Enable NEON for unittests on ios 64 bit.

BUILD.gn

 # Copyright 2014 The LibYuv Project Authors. All rights reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS. All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("libyuv.gni")
 import("//testing/test.gni")
@@ skipping 164 matching lines @@
     configs += [ ":libyuv_unittest_warnings_config" ]
 
     public_deps = [ "//testing/gtest" ]
     public_configs = [ ":libyuv_unittest_config" ]
 
     defines = []
 
     if (is_linux) {
       cflags = [ "-fexceptions" ]
     }
-    if (is_ios && target_cpu=="arm64") {
-      defines += [ "LIBYUV_DISABLE_NEON" ]
-    }
     if (is_ios) {
       configs -= [ "//build/config/compiler:default_symbols" ]
       configs += [ "//build/config/compiler:symbols" ]
       cflags = [ "-Wno-sometimes-uninitialized" ]
     }
     if (!is_ios && !libyuv_disable_jpeg) {
       defines += [ "HAVE_JPEG" ]
     }
     if (is_android) {
       deps += [ "//testing/android/native_test:native_test_native_code" ]
@@ skipping 41 matching lines @@
 
   executable("psnr") {
     sources = [
       # sources
       "util/psnr_main.cc",
       "util/psnr.cc",
       "util/ssim.cc"
     ]
     deps = [ ":libyuv" ]
 
-    if (is_ios && target_cpu=="arm64") {
-      # TODO(fbarchard): Enable Neon. See https://crbug.com/646279
-      defines = [ "LIBYUV_DISABLE_NEON" ]
-    }
     if (!is_ios && !libyuv_disable_jpeg) {
       defines = [ "HAVE_JPEG" ]
     }
   }
 
   executable("cpuid") {
     sources = [
       # sources
       "util/cpuid.c"
     ]
     deps = [ ":libyuv" ]
   }
 }