remove logic for avoiding nonredistributable blobs

the --nuke option in ifdtool will be used instead, to nuke
the ME regions in specific rom sets (and cbfstool will be
used to delete mrc.bin files from rom sets)

the new method being implemented is heavier on disk io, but
simplifies lbmk, and disk io could still be optimised in
the following ways:

* when copying roms from boards with ME in them, use
  ifdtool --nuke to get filename.rom.new, and *move* (not copy)
  filename.rom.new to the new destination (for use with tar)

* possibly modify ifdtool to make efficient use of mmap for
  disk i/o; it currently loads entire roms into an allocated
  buffer in memory