Update CleanSpec.mk for the common testcase directories.

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

Bug: 67456333
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
(cherry picked from commit 7fe57cfdcdc086871300d37cf6e80bc94f85b5ee)
Merged-In: I77529021e852af35571fb99537d87100010b47af
diff --git a/CleanSpec.mk b/CleanSpec.mk
index 3c8d6ce..b311470 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -374,6 +374,9 @@
 # $(PRODUCT_OUT)/recovery/root/sdcard goes from symlink to folder.
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/recovery/root/sdcard)
 
+$(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
 # ************************************************