Work around odd behavior in kexec-lite: it requires that there be no INTERP
section (just an assertion, no good reason for this) and ignores the
defined entry point for the executable, beginning execution at the beginning
of the first PT_LOAD section.

Solve these by (if possible) dropping INTERP and arranging things such that
the first instruction of the first PT_LOAD section is, in fact, the entry
point. This allows stock kexec-lite, and thus petitboot, to directly load
and start the FreeBSD kernel from Linux.

Still panics a little ways in with an SMP error, but that is a problem for
another day.