vendor/getinfo: Teach it about sourceslist-list-format

This makes it easier to write a generic subsitution tool for
handling substitutions in apt-key.in and sources.list.in

Gbp-Dch: ignore

vendor/getinfo

@@ -58,7 +58,7 @@ case "$1" in
 debian-stable-codename|debian-oldstable-codename|debian-testing-codename|ubuntu-codename)
 	getrawfield "$1" "$VERBATIM"
 	;;
-keyring-package|keyring-filename|keyring-master-filename|keyring-removed-filename|keyring-uri|current-codename)
+sourceslist-list-format|keyring-package|keyring-filename|keyring-master-filename|keyring-removed-filename|keyring-uri|current-codename)
 	exec $0 'vendor' "$@"
 	;;
 vendor)