Move to debhelper compat level 10

- stop using dh --parallel, it's the default now
  - don't use autoreconf and systemd addons explicitly, they are
    the default now

debian/control

@@ -9,9 +9,7 @@ Build-Depends:
  attr,
  bison,
  cpio,
- debhelper (>= 9),
- dh-autoreconf,
- dh-systemd,
+ debhelper (>= 10~),
  docbook-xml,
  docbook-xsl,
  e2fslibs-dev,