More consistent use of 64-bit build variable.

Set up TARGET_IS_64_BIT and HOST_IS_64_BIT early so we don't need 2
mechanisms to judge if it's 64-bit build;
Remove the unnecessary 32-bit host variables.

Change-Id: I08d6d4d9ea70f91135fe2ee05463fb9a0d1cee42
diff --git a/core/target_test_internal.mk b/core/target_test_internal.mk
index 87503ea..95d4159 100644
--- a/core/target_test_internal.mk
+++ b/core/target_test_internal.mk
@@ -31,5 +31,5 @@
 $(error $(LOCAL_PATH): Do not set LOCAL_MODULE_PATH_64 when building test $(LOCAL_MODULE))
 endif
 
-LOCAL_MODULE_PATH_32 := $(TARGET_OUT_DATA_NATIVE_TESTS)/$(LOCAL_MODULE)
-LOCAL_MODULE_PATH_64 := $(TARGET_OUT_DATA_NATIVE_TESTS)64/$(LOCAL_MODULE)
+LOCAL_MODULE_PATH_64 := $(TARGET_OUT_DATA_NATIVE_TESTS)/$(LOCAL_MODULE)
+LOCAL_MODULE_PATH_32 := $($(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_DATA_NATIVE_TESTS)/$(LOCAL_MODULE)