writeisofs: also boots plain binaries with -B
writeisofs: also boots plain binaries with -B

With -n -b file, a.out boot images can be used for CD booting;
with the new -n -B file option, plain binary (like bootxx_cd9660)
can be used instead.
Restore working the -h and -f options while there.
And add a new -F option for 2.8MB floppy image.

veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi