m68k: fixup_next_boot_floppy: force bootblock at 8k to fit before tgz

We don't have room for disklabel copies anymore.

+ style fixes

Change-Id: I22502167a4f5f8bc3df1b017072461d77a299b16
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3100
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

m68k: fixup_next_boot_floppy: use Haiku names, write copies

Change-Id: I99b007d8c67f278f5bb7a784ea0e56fdd15209c0
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3099
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

m68k: fixup_next_boot_floppy tool (actually writes the disklabel)

Next floppies actually do have a "disk label" (partitionning scheme),
the boot block being later on the disk.

This commit generates an identical label to the image I have here (but
not the copies at other sectors), including the checksum.

Change-Id: I7f939c26e70e3626d9af7a3eb342cfd32c298e3d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3098
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>