Add the list of makefiles that were also included by product config to dumpconfig.

In this entry, the first list of files is the inherit-product stack, and
the second one is the list of files included by the file at the top of
the stack that just finished processing

Test: build/make/ci/dump_product_config
Change-Id: I826b1ec6fa1319b8f0cdfaacc6ccf999ce93d9f1
diff --git a/core/dumpconfig.mk b/core/dumpconfig.mk
index 8991d6e..eb4c822 100644
--- a/core/dumpconfig.mk
+++ b/core/dumpconfig.mk
@@ -68,7 +68,7 @@
 # Args:
 #   $(1): include stack
 define dump-import-done
-$(eval $(file >> $(DUMPCONFIG_FILE),imported,$(strip $(1))))
+$(eval $(file >> $(DUMPCONFIG_FILE),imported,$(strip $(1)),$(filter-out $(1),$(MAKEFILE_LIST))))
 endef
 
 # Args: