ktest: Add native support for syslinux boot loader

I installed Fedora 17 which no longer supports grub v1. I worked
with grub2 for a while, but there's so many issues with it and automated
rebooting, that I decided to switch to syslinux. Instead of using
the REBOOT_SCRIPT and add customized changes to get syslinux booted,
I thought it better to make ktest aware of syslinux and add options
to simplify the use of syslinux on a target test box.

Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: John 'Warthog9' Hawley <warthog9@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>