Finish refactoring tests to NATIVE_TESTS

Now that the source trees all use NATIVE_TESTS for intermediate files
and generated sources, make it a requirement.

Change-Id: Id5718fabe63f6e8dde7981a6f0f5bd89e0ec7ee5
diff --git a/core/host_test_internal.mk b/core/host_test_internal.mk
index 70f011b..473815b 100644
--- a/core/host_test_internal.mk
+++ b/core/host_test_internal.mk
@@ -23,3 +23,7 @@
 ifdef LOCAL_MODULE_PATH_64
 $(error $(LOCAL_PATH): Do not set LOCAL_MODULE_PATH_64 when building test $(LOCAL_MODULE))
 endif
+
+ifndef LOCAL_MODULE_RELATIVE_PATH
+LOCAL_MODULE_RELATIVE_PATH := $(LOCAL_MODULE)
+endif