Remove `armv7-a`.

Non-neon armv7 hasn't been supported for OS builds for many years now.

Change-Id: I230cd0b20cc166a59b622c9cd82b7f06ef3ca3b0
diff --git a/android/arch_list.go b/android/arch_list.go
index 4233456..f1289a3 100644
--- a/android/arch_list.go
+++ b/android/arch_list.go
@@ -16,7 +16,6 @@
 
 var archVariants = map[ArchType][]string{
 	Arm: {
-		"armv7-a",
 		"armv7-a-neon",
 		"armv8-a",
 		"armv8-2a",