Clean junit4-target files

Incremental builders were failing to detect a real build breakage,
but treehugger was seeing it and failing all changes in presubmit.
Clean the stale files so it doesn't happen again.

Bug: 34528444
Test: cleans
Change-Id: I0320bad5f5f9292e88d03be3e29606833d18cb55

CleanSpec.mk

@@ -44,6 +44,8 @@
 #$(call add-clean-step, find $(OUT_DIR) -type f -name "IGTalkSession*" -print0 | xargs -0 rm -f)
 #$(call add-clean-step, rm -rf $(PRODUCT_OUT)/data/*)
 
+$(call add-clean-step, rm -rf $(OUT_DIR)/target/common/obj/JAVA_LIBRARIES/junit4-target_intermediates)
+
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************