Clean up the crt*.o files.

To fix incremental build failure caused by
https://android-review.googlesource.com/41940

Change-Id: I9a977fe6e26fefaababdbb5d498b63e37884a4be
diff --git a/CleanSpec.mk b/CleanSpec.mk
index 8f2cf3a..b4b99b8 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -138,6 +138,7 @@
 $(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 $(PRODUCT_OUT)/obj/EXECUTABLES)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/lib/*.o)
 
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST