Enable multidex for dx

Enable multidex for dx where it is already enabled for jack.

Test: m -j ANDROID_COMPILE_WITH_JACK=false FrameworksServicesTests
Change-Id: I55a6951ef471930e7737d9f93aaaffb567d4a580
diff --git a/services/tests/servicestests/Android.mk b/services/tests/servicestests/Android.mk
index 2a8f4a3..bb4507d 100644
--- a/services/tests/servicestests/Android.mk
+++ b/services/tests/servicestests/Android.mk
@@ -52,6 +52,7 @@
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 
 LOCAL_JACK_FLAGS := --multi-dex native
+LOCAL_DX_FLAGS := --multi-dex
 
 LOCAL_STATIC_JAVA_LIBRARIES += ub-uiautomator