Update PKGBUILDS for pwmt apps.

This implements the not-so-new API for VCS PKGBUILDS. Also it adds the
necessary gitignore files because otherwise we start storing git repos
here, which is not good.

Signed-off-by: Ignas Anikevicius (gns_ank) <anikevicius@gmail.com>
Add mpv, which will be my player of choice from now on

Signed-off-by: Ignas Anikevicius (gns_ank) <anikevicius@gmail.com>