Update CleanSpec.mk for the common testcase directories.

Fix an issue with incremental builds and the new common
testcase directories.

Bug: None
Test: Removed https://android-review.googlesource.com/#/c/234478/
      then ran `m cts-platform-version-check` then reapplied the
      change to verify the failure. Then applied this new change
      to verify the problem was resolved.

Change-Id: I77529021e852af35571fb99537d87100010b47af
diff --git a/CleanSpec.mk b/CleanSpec.mk
index bbeac6c..b9f6e13 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -395,6 +395,9 @@
 $(call add-clean-step, rm -rf $(TARGET_OUT_COMMON_INTERMEDIATES)/APPS/*_intermediates/src)
 $(call add-clean-step, rm -rf $(TARGET_OUT_COMMON_INTERMEDIATES)/JAVA_LIBRARIES/*_intermediates/src)
 
+$(call add-clean-step, rm -rf $(HOST_OUT_TESTCASES))
+$(call add-clean-step, rm -rf $(TARGET_OUT_TESTCASES))
+
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************