[arch-general] Reboot - Versioned Kernel Installs

[Robert Howard]

Why not just copy the old kernel image, modules and initrd image somewhere
by hand before you upgrade kernels. If we try to make this automated it
isn't going to be kiss. I used to do this way back in the day by including
the entire kernel version in the pkgver and giving the images longer names.
It was possible to have concurrently installed kernels. Check out how some
of the AUR kernels manage to be the same kernel version as the official
without causing issues.