debian: require dh-autoreconf for autoreconf.mk to be present
debian: on Debian, don't ship upstart script
Revert "debian: on Debian, don't ship upstart script"

This reverts commit d5e9611c1cc903410f42a8272898b31404559c6f.

We can't request dh-autoreconf and have a buggy dh_installinit at the
same time. Let's remove this code about upstart. This only needs to be
fixed in backports.