Please add mac package dependency to allow APE support

[Uqbar]

shnsplit needs mac (http://supermmx.org/linux/mac/) in order to really support APE (Monkey's Audio).
I've manually compiled the sources I've got from here (http://etree.org/shnutils/shntool/support/formats/ape/unix/3.99-u4-b5/mac-3.99-u4-b5.tar.gz) with success.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: shntool 3.0.7-1ubuntu1
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic-pae 3.0.4
Uname: Linux 3.0.0-12-generic-pae i686
ApportVersion: 1.23-0ubuntu3
Architecture: i386
Date: Mon Oct 31 10:48:16 2011
InstallationMedia: Kubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
ProcEnviron:
 LANGUAGE=
 LC_COLLATE=C
 PATH=(custom, user)
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
SourcePackage: shntool
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.