implement accessibility support in archiso

Makefile

...g/airootfs/etc/systemd/system/livecd-alsa-unmuter.service

...gs/releng/airootfs/etc/systemd/system/livecd-talk.service

...ystemd/system/multi-user.target.wants/livecd-talk.service

...emd/system/sound.target.wants/livecd-alsa-unmuter.service

configs/releng/airootfs/root/.zlogin

configs/releng/airootfs/usr/local/bin/livecd-sound

...leng/airootfs/usr/local/share/livecd-sound/asound.conf.in

...g/efiboot/loader/entries/archiso-x86_64-speech-linux.conf

configs/releng/efiboot/loader/loader.conf

configs/releng/packages.x86_64

configs/releng/syslinux/archiso_head.cfg

configs/releng/syslinux/archiso_sys-linux.cfg

configs/releng/syslinux/archiso_sys.cfg