bytes of useless zeroes in the final image.

link-time check for section overlaps.  (In order to avoid wasting
space in the executable image, .bss16 will overlap with the following
section, which is .text).

This reverts commit 9dc2515d7e.

I want "make" to actually build something.

start of the non-prefix blocks in the loaded image, and rely on the
image ordering.  This should make introducing compression much easier.

"rep movsb".

in a long loop before giving up on them.  Record method which worked
and default to that method on next attempt.

etherboot.h is only now used by drivers that have not been updated to
the new API.

Kill off use of etherboot.h outside drivers/net.

optimisation of only trying to do so when necessary.