reachableroots: sort the smartset in the pure version too
Changeset
be8a4e0800d8 uses smartset lazy sorting for the C version. We need to
apply the same to the pure version for consistency. This is fixing the tests
with --pure.
builddeb: actually run make when building the deb (
issue4778)
As of this change, we no longer produce broken debs, but I've already
got followups written that will produce much more standard-looking
packages and test the resulting packages.