Fix dracut Debian/Ubuntu packaging

This commit ensures make(1) targets that build .deb packages fail if
alien(1) can't convert all .rpm files; additionally it also updates
the zfs-dracut package name which was changed to "noarch" in ca4e5a7.

Reviewed-by: Neal Gompa <ngompa@datto.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #8990
Closes #8991