Remove mentions of libmad

audacity.dox.in

help/audacity.1

lib-src/audacity-patches.txt

linux/packages/arch/PKGBUILD

linux/packages/arch/dependencies.sh

linux/packages/fedora34/audacity.spec

linux/packages/fedora34/dependencies.sh

linux/packages/ubuntu-20.04/debian/control

linux/packages/ubuntu-20.04/dependencies.sh

linux/required_libraries.md

linux/ubuntu-focal/dependencies.sh

linux/ubuntu-focal/entrypoint.sh

src/AboutDialog.cpp