introduce android_x64 build target

build/android.gypi

Index: build/android.gypi
diff --git a/build/android.gypi b/build/android.gypi
index 5d3b25a74636ca4b8bf430b94a7835673dd49dc4..533250e7f56f966d3f0bf77685cc3d9b78184cb3 100644
--- a/build/android.gypi
+++ b/build/android.gypi
@@ -43,7 +43,13 @@
           'android_stlport': '<(android_toolchain)/sources/cxx-stl/stlport/',
         },
         'android_include': '<(android_sysroot)/usr/include',
-        'android_lib': '<(android_sysroot)/usr/lib',
+        'conditions': [
+          ['target_arch=="x64"', {
+            'android_lib': '<(android_sysroot)/usr/lib64',
+          }, {
+            'android_lib': '<(android_sysroot)/usr/lib',
+          }],
+        ],
         'android_stlport_include': '<(android_stlport)/stlport',
         'android_stlport_libs': '<(android_stlport)/libs',
       }, {
@@ -52,7 +58,13 @@
           'android_stlport': '<(android_ndk_root)/sources/cxx-stl/stlport/',
         },
         'android_include': '<(android_sysroot)/usr/include',
-        'android_lib': '<(android_sysroot)/usr/lib',
+        'conditions': [
+          ['target_arch=="x64"', {
+            'android_lib': '<(android_sysroot)/usr/lib64',
+          }, {
+            'android_lib': '<(android_sysroot)/usr/lib',
+          }],
+        ],
         'android_stlport_include': '<(android_stlport)/stlport',
         'android_stlport_libs': '<(android_stlport)/libs',
       }],
@@ -227,7 +239,7 @@
         'target_conditions': [
           ['_type=="executable"', {
             'conditions': [
-              ['target_arch=="arm64"', {
+              ['target_arch=="arm64" or target_arch=="x64"', {
                 'ldflags': [
                   '-Wl,-dynamic-linker,/system/bin/linker64',
                 ],