For whatever reason Debian build scripts (e.g. debhelper and dbclean)
seem to have changed in such a way to be Debian 4.0 ("etch") unfriendly.

So when the ./build_debian.sh script is called on a Debian 4.0 system,
it fails saying the debhelper is too old. That can be fixed by editing
the 'control' file, changing this line:
    Build-Depends: debhelper (>> 7), libtool, libcam-dev [kfreebsd-i386 kfreebsd-amd64]
to:
    Build-Depends: debhelper, libtool, libcam-dev [kfreebsd-i386 kfreebsd-amd64]

The script then dies in dbclean and the hack to get around that is to
edit the 'compat' file. It contains "7" which needs to be changed to
"4". Evidently "4" is deprecated and "5" is preferable and should work.