Fix some dh missing

This implments the changes to clear our issues reported by dh_missing and discussed for preferences in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=919484

The one thing it does not tackle is usr/lib/x86_64-linux-gnu/libnss_libvirt_guest.so.2 as I don't know yet what to do with it.

Finally please take a look at the doc changes if you are ok, if you don't want to add those lets at least ignore them then.