user to interrupt autoboot process at all. Currently, even when
`autoboot_delay' is set to 0, loader(8) still allows autoboot process to be
interrupted by pressing any key on the console when the loader reads kernel
and modules from the disk. In some cases (i.e. untrusted environment) such
behaviour is highly indesirable and user should not be allowed to interfere
with the autoboot process at all.
Sponsored by: PBXpress Inc.
MFC after: 3 days
4d87b291ad