Revert "Only test for ARM v7 when doing an ARM build"

This reverts commit c82d6571ba7c10ab287e59968cdd6fe7aa68751a and
commit d7a34d91def077ae0438f710f157e30f38539abe.

This broke the cts build, which uses ARM v5.

Bug: 5495373
Change-Id: I2ce84d2bee5a4f710d88ffda631882324f8b86da
diff --git a/Android.mk b/Android.mk
index 0e304f2..c69a2cc 100644
--- a/Android.mk
+++ b/Android.mk
@@ -18,12 +18,17 @@
 BASE_PATH := $(call my-dir)
 include $(CLEAR_VARS)
 
+# Two ways to control which JS engine is used:
+# 1. use JS_ENGINE environment variable, value can be either 'jsc' or 'v8'
+#    This is the preferred way.
+# 2. if JS_ENGINE is not set, or is not 'jsc' or 'v8', this makefile picks
+#    up a default engine to build.
+#    To help setup buildbot, a new environment variable, USE_ALT_JS_ENGINE,
+#    can be set to true, so that two builds can be different but without
+#    specifying which JS engine to use.
+
 # Build libv8 and v8shell
 ifeq ($(TARGET_ARCH),arm)
-    ifneq ($(strip $(ARCH_ARM_HAVE_ARMV7A)),true)
-        $(error V8 requires ARM v7)
-    endif
-
     ENABLE_V8_SNAPSHOT = true
     include $(BASE_PATH)/Android.mksnapshot.mk
     include $(BASE_PATH)/Android.libv8.mk