Adds support for building arm64 Android.

tools/gyp/configurations_android.gypi

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # Definitions for building standalone Dart binaries to run on Android.
 # This is mostly excerpted from:
 # http://src.chromium.org/viewvc/chrome/trunk/src/build/common.gypi
 
 {
   'variables': {
@@ skipping 26 matching lines @@
             'cflags': [
               '-U__linux__',  # Don't allow toolchain to claim -D__linux__
               '-ffunction-sections',
               '-funwind-tables',
               '-fstack-protector',
               '-fno-short-enums',
               '-finline-limit=64',
               '-Wa,--noexecstack',
             ],
           }],
-          # Settings for building host targets using the system toolchain.
-          ['_toolset=="host"', {
-            'cflags': [ '-m32', '-pthread' ],
-          }],
         ],
       },
       'Dart_Android_Debug': {
         'abstract': 1,
         'defines': [
           'DEBUG',
         ],
         'conditions': [
           ['c_frame_pointers==1', {
             'cflags': [
@@ skipping 79 matching lines @@
               '-Wl,--gc-sections',
               '-Wl,-z,nocopyreloc',
               # crtbegin_dynamic.o should be the last item in ldflags.
               '<(android_ndk_lib)/crtbegin_dynamic.o',
             ],
             'ldflags!': [
               '-pthread',  # Not supported by Android toolchain.
             ],
           }],
           ['_toolset=="host"', {
+            'cflags': [ '-m32', '-pthread' ],
             'ldflags': [ '-m32', '-pthread' ],
           }],
         ],
       },
       'Dart_Android_arm_Base': {
         'abstract': 1,
         'variables': {
           'android_sysroot': '<(android_ndk_root)/platforms/android-14/arch-arm',
           'android_ndk_include': '<(android_sysroot)/usr/include',
           'android_ndk_lib': '<(android_sysroot)/usr/lib',
@@ skipping 35 matching lines @@
               '-Wl,--gc-sections',
               '-Wl,-z,nocopyreloc',
               # crtbegin_dynamic.o should be the last item in ldflags.
               '<(android_ndk_lib)/crtbegin_dynamic.o',
             ],
             'ldflags!': [
               '-pthread',  # Not supported by Android toolchain.
             ],
           }],
           ['_toolset=="host"', {
+            'cflags': [ '-m32', '-pthread' ],
             'ldflags': [ '-m32', '-pthread' ],
           }],
         ],
-      },
+      },  # Dart_Android_arm_Base
+      'Dart_Android_arm64_Base': {
+        'abstract': 1,
+        'variables': {
+          'android_sysroot': '<(android_ndk_root)/platforms/android-L/arch-arm64',
+          'android_ndk_include': '<(android_sysroot)/usr/include',
+          'android_ndk_lib': '<(android_sysroot)/usr/lib',
+        },
+        'target_conditions': [
+          ['_toolset=="target"', {
+            'cflags': [
+              '-fPIE',
+              '--sysroot=<(android_sysroot)',
+              '-I<(android_ndk_include)',
+              '-I<(android_ndk_root)/sources/cxx-stl/stlport/stlport',
+            ],
+            'target_conditions': [
+              ['_type=="executable"', {
+                'ldflags!': ['-Wl,--exclude-libs=ALL,-shared',],
+              }],
+              ['_type=="shared_library"', {
+                'ldflags': ['-Wl,-shared,-Bsymbolic',],
+              }],
+            ],
+            'ldflags': [
+              'arm64', '>(_type)', 'target',
+              '-nostdlib',
+              '-Wl,--no-undefined',
+              # Don't export symbols from statically linked libraries.
+              '-Wl,--exclude-libs=ALL',
+              '-Wl,-rpath-link=<(android_ndk_lib)',
+              '-L<(android_ndk_lib)',
+              '-L<(android_ndk_root)/sources/cxx-stl/stlport/libs/arm64-v8a',
+              '-z',
+              'muldefs',
+              '-Bdynamic',
+              '-pie',
+              '-Wl,-dynamic-linker,/system/bin/linker64',
+              '-Wl,--gc-sections',
+              '-Wl,-z,nocopyreloc',
+              # crtbegin_dynamic.o should be the last item in ldflags.
+              '<(android_ndk_lib)/crtbegin_dynamic.o',
+            ],
+            'ldflags!': [
+              '-pthread',  # Not supported by Android toolchain.
+            ],
+          }],
+          ['_toolset=="host"', {
+            'ldflags': [ '-pthread' ],
+          }],
+        ],
+      },  # Dart_Android_arm64_Base
     },  # configurations
   },  # target_defaults
 }