build: rename aarch64 target to arm64

Rename aarch64 build targets to arm64.  The gcc toolchain is still
aarch64.

Change-Id: Ia92d8a50824e5329cf00fd6f4f92eae112b7f3a3
diff --git a/envsetup.sh b/envsetup.sh
index 13cc6f7..3ec6cce 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -132,7 +132,7 @@
             ;;
         arm) toolchaindir=arm/arm-linux-androideabi-$targetgccversion/bin
             ;;
-        aarch64) toolchaindir=aarch64/aarch64-linux-android-$targetgccversion/bin
+        arm64) toolchaindir=aarch64/aarch64-linux-android-$targetgccversion/bin
             ;;
         mips) toolchaindir=mips/mipsel-linux-android-$targetgccversion/bin
             ;;
@@ -436,7 +436,7 @@
 add_lunch_combo aosp_x86-eng
 add_lunch_combo aosp_mips-eng
 add_lunch_combo aosp_x86_64-eng
-add_lunch_combo aosp_aarch64-eng
+add_lunch_combo aosp_arm64-eng
 add_lunch_combo vbox_x86-eng
 
 function print_lunch_menu()