Prepare switch from a64 to arm64

build/toolchain.gypi

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 250 matching lines @@
                   }],
                 ],
                 'defines': [
                   'ARM_TEST',
                 ],
               }],
             ],
           }],  # _toolset=="target"
         ],
       }],  # v8_target_arch=="arm"
-      ['v8_target_arch=="a64"', {
+      ['v8_target_arch=="a64" or v8_target_arch=="arm64"', {
         'defines': [
           'V8_TARGET_ARCH_A64',
         ],
       }],
       ['v8_target_arch=="ia32"', {
         'defines': [
           'V8_TARGET_ARCH_IA32',
         ],
       }],  # v8_target_arch=="ia32"
       ['v8_target_arch=="mipsel"', {
@@ skipping 124 matching lines @@
                 'ldflags': [ '<(m32flag)' ],
               }],
             ],
             'xcode_settings': {
               'ARCHS': [ 'i386' ],
             },
           }],
         ],
       }],
       ['(OS=="linux" or OS=="android") and \
-        (v8_target_arch=="x64" or v8_target_arch=="a64")', {
+        (v8_target_arch=="x64" or v8_target_arch=="a64" or \
+         v8_target_arch=="arm64")', {
         # Check whether the host compiler and target compiler support the
         # '-m64' option and set it if so.
         'target_conditions': [
           ['_toolset=="host"', {
             'variables': {
               'm64flag': '<!(($(echo ${CXX_host:-$(which g++)}) -m64 -E - > /dev/null 2>&1 < /dev/null) && echo "-m64" || true)',
             },
             'cflags': [ '<(m64flag)' ],
             'ldflags': [ '<(m64flag)' ],
           }],
@@ skipping 268 matching lines @@
                 'OptimizeReferences': '2',
                 'EnableCOMDATFolding': '2',
               },
             },
           }],  # OS=="win"
         ],  # conditions
       },  # Release
     },  # configurations
   },  # target_defaults
 }