This should make it less difficult for people to add kernel options for
debugging. Without a prompt/timeout the user must be holding down space
or some other key while syslinux loads but it may not be possible for
the user to do so provide input quite that fast. Only a half second to
avoid needlessly increasing boot times in the common case.
Now with SYSLINUX 6 we can use the same bootloader on EFI and BIOS
systems. This replaces our previous reliance on building default kernel
options into the kernel image itself.
