Use BOARD_USES_VENDORIMAGE to detect vendor image presence - DO NOT MERGE

When building without vendor/... in the tree, we won't be creating a
vendorimage, so BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE won't be defined. But
we still need to use the vendor image that will be present.

Bug: 31545062
Bug: 30040825
Change-Id: I756adc615aea11da60da4d3a4568caca9fed93ab
diff --git a/CleanSpec.mk b/CleanSpec.mk
index b3661e4..5d335b5 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -56,3 +56,4 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/EXECUTABLES/lmkd_intermediates/import_includes)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/SHARED_LIBRARIES/libsysutils_intermediates/import_includes)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/bin/grep $(PRODUCT_OUT)/system/bin/toolbox)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/root/vendor)