Clean step for libc.

Change-Id: I6e11464eedea7ce073a3278e07825f777a32f62a
diff --git a/CleanSpec.mk b/CleanSpec.mk
index 2bcc1b6..8f2cf3a 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -135,6 +135,10 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/APPS/*)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/build.prop)
 
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/STATIC_LIBRARIES)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/SHARED_LIBRARIES)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/EXECUTABLES)
+
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************