Allow to opt out both multilib in native test.

This fixes error no 64-bit libdvm for dalvik-vm-unit-tests.

Change-Id: Ieb21b3b636facbff32c62bca8bba1df6d21377c6
diff --git a/core/native_test.mk b/core/native_test.mk
index bc7f2e7..93b7e1a 100644
--- a/core/native_test.mk
+++ b/core/native_test.mk
@@ -5,6 +5,10 @@
 
 include $(BUILD_SYSTEM)/target_test_internal.mk
 
+ifndef LOCAL_MULTILIB
+ifndef LOCAL_32_BIT_ONLY
 LOCAL_MULTILIB := both
+endif
+endif
 
 include $(BUILD_EXECUTABLE)