Add aosp_aarch64-eng to the default lunch menu.

Change-Id: I55f6ab6ea90670def30796fdce76c27031ecef01
diff --git a/envsetup.sh b/envsetup.sh
index bc4f6a1..289fdb2 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -436,6 +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 vbox_x86-eng
 
 function print_lunch_menu()