Mark android-support-design as AAPT2 only library.

Test: None
Change-Id: I32e9e3933c7903b8dceaf60d0c491eda53ebf420
diff --git a/design/Android.mk b/design/Android.mk
index 26017b4..7ee463f 100644
--- a/design/Android.mk
+++ b/design/Android.mk
@@ -27,6 +27,7 @@
 # in their makefiles to include the resources and their dependencies in their package.
 include $(CLEAR_VARS)
 LOCAL_USE_AAPT2 := true
+LOCAL_AAPT2_ONLY := true
 LOCAL_MODULE := android-support-design
 LOCAL_SDK_VERSION := $(SUPPORT_CURRENT_SDK_VERSION)
 LOCAL_SRC_FILES := \