Forth version of EFI autoresizing

r331321 delegated autoresizing to an efi-autoresizecons command that
currently is expected to be done in forth/lua prior to drawing anything
useful.

Add the Forth version of the lua addition in r331321, hook efi.4th up to be
installed.

efiboot? was written by dteske@; anything outside of that may be blamed on
me.