- prefix the patches with 'syslinux-'
- make sure that they are actually applied
- add upstream patch for cli cmdline parsing

This should fix the issue where cmdline options are not added to kernel.

http://www.syslinux.org/archives/2015-September/024317.html
http://www.syslinux.org/archives/2015-September/024318.html

minor fix that makes it work with bash

on lxc we dont have the boot device available so extlinux will fail.
We cannot check for `openrc --sys` because apk run the trigger in chroot
and grsecurity will prevent openrc access /proc/1/environment.

So we simply add a --warn-only option and use that from trigger.

ref #3273