FTBFS again on Hurd

This is another case of legacy/trac#5355 (moved) which was introduced by ba3a5f82f11388237a3ba4995ddf0b6ffaaf492a. Found this while looking at the Tor builds on Debian (see https://buildd.debian.org/status/logs.php?pkg=tor&arch=hurd-i386).

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information