reproducible Arch Linux: disable SSL checks for pacman-git as well

When using profitbricks-build4-amd64 with future time, we need to
disable SSL checks as they don't mean anything anyway. We already do so
for reproducible_build_archlinux_pkg.sh, but there is one more place
where we build packages. :)

Signed-off-by: Holger Levsen <holger@layer-acht.org>