Build for Android x64

tools/gyp/configurations_android.gypi

Index: tools/gyp/configurations_android.gypi
diff --git a/tools/gyp/configurations_android.gypi b/tools/gyp/configurations_android.gypi
index 0d6133dabf1cdda3ab5af9448f9538f056571cfc..8708d6dafadbd9cbf9a1333c76f85fb3132190ec 100644
--- a/tools/gyp/configurations_android.gypi
+++ b/tools/gyp/configurations_android.gypi
@@ -148,6 +148,58 @@
           }],
         ],
       },
+      'Dart_Android_x64_Base': {
+        'abstract': 1,
+        'variables': {
+          'android_sysroot': '<(android_ndk_root)/platforms/android-21/arch-x86_64',
+          'android_ndk_include': '<(android_sysroot)/usr/include',
+          'android_ndk_lib': '<(android_sysroot)/usr/lib64',
+        },
+        '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': [
+              'x64', '>(_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/x86_64',
+              '-z',
+              'muldefs',
+              '-Bdynamic',
+              '-pie',
+              '-Wl,-dynamic-linker,/system/bin/linker',
+              '-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': [ '-pthread' ],
+            'ldflags': [ '-pthread' ],
+          }],
+        ],
+      },
       'Dart_Android_arm_Base': {
         'abstract': 1,
         'variables': {