Rename A64 port to ARM64 port

Makefile.android

Index: Makefile.android
diff --git a/Makefile.android b/Makefile.android
index ea2c6e284bd9a1b6f7d633cc2b8faf93f9f9f7e4..f4e144f280f280b356ce92de02d26229ef408d01 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_a64 android_mipsel
+ANDROID_ARCHES = android_ia32 android_arm android_arm64 android_mipsel
 MODES = release debug
 
 # Generates all combinations of ANDROID ARCHES and MODES,
@@ -53,8 +53,8 @@ ifeq ($(ARCH), android_arm)
   TOOLCHAIN_PREFIX = $(TOOLCHAIN_ARCH)
   TOOLCHAIN_VER = 4.6
 else
-  ifeq ($(ARCH), android_a64)
-    DEFINES  = target_arch=a64 v8_target_arch=a64 android_target_arch=arm64
+  ifeq ($(ARCH), android_arm64)
+    DEFINES  = target_arch=arm64 v8_target_arch=arm64 android_target_arch=arm64
     TOOLCHAIN_ARCH = aarch64-linux-android
     TOOLCHAIN_PREFIX = $(TOOLCHAIN_ARCH)
     TOOLCHAIN_VER = 4.8