This imports the MD5 code used by other utilities and creates
a function for checking the provided NK.bin against known original
firmware checksums. Integration into mknkboot and beastpatcher is
also added.
For the sake of consistency with beastpatcher, mknkboot had its
printf statements rewrote to print to stderr like beastpatcher
does.
Change-Id: I0e52271d8d627a5b02302ab5cd1da2815b7cec1e
