A64: Add Android_a64 build target

Makefile.android

Index: Makefile.android
diff --git a/Makefile.android b/Makefile.android
index aeff01c665e1da1c9c6fc51daff0bb6c8f671bf6..68ebe848d7aceaf500f46b2f61005741873947dc 100644
--- a/Makefile.android
+++ b/Makefile.android
@@ -26,7 +26,7 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 # Those definitions should be consistent with the main Makefile
-ANDROID_ARCHES = android_ia32 android_arm android_mipsel
+ANDROID_ARCHES = android_ia32 android_arm android_a64 android_mipsel
 MODES = release debug
 
 # Generates all combinations of ANDROID ARCHES and MODES,
@@ -50,16 +50,21 @@ ifeq ($(ARCH), android_arm)
   DEFINES += arm_neon=0 armv7=1
   TOOLCHAIN_ARCH = arm-linux-androideabi-4.6
 else
-  ifeq ($(ARCH), android_mipsel)
-    DEFINES  = target_arch=mipsel v8_target_arch=mipsel android_target_arch=mips
-    DEFINES += mips_arch_variant=mips32r2
-    TOOLCHAIN_ARCH = mipsel-linux-android-4.6
+  ifeq ($(ARCH), android_a64)
+    DEFINES  = target_arch=a64 v8_target_arch=a64 android_target_arch=aarch64
+    TOOLCHAIN_ARCH = aarch64-linux-android-4.8
   else
-    ifeq ($(ARCH), android_ia32)
-      DEFINES = target_arch=ia32 v8_target_arch=ia32 android_target_arch=x86
-      TOOLCHAIN_ARCH = x86-4.6
+    ifeq ($(ARCH), android_mipsel)
+      DEFINES  = target_arch=mipsel v8_target_arch=mipsel
+      DEFINES += android_target_arch=mips mips_arch_variant=mips32r2
+      TOOLCHAIN_ARCH = mipsel-linux-android-4.6
     else
-      $(error Target architecture "${ARCH}" is not supported)
+      ifeq ($(ARCH), android_ia32)
+        DEFINES = target_arch=ia32 v8_target_arch=ia32 android_target_arch=x86
+        TOOLCHAIN_ARCH = x86-4.6
+      else
+        $(error Target architecture "${ARCH}" is not supported)
+      endif
     endif
   endif
 endif