Apparently this doesn't work for MIPS, since BFD declares different
processors (which it calls "machines") to be incompatible. I'm not
quite familiar with MIPS, but I suppose this is not quite true, but
that the various MIPS processors cannot be mapped on a one-dimensional
quantity that expresses the features of the various CPU's. That could
be a valid reason why the MIPS "compatibility function" is written the
way it is. Perhaps it can be improved? If so, I think that's the way
to go. Otherwise, I think you should register for all CPU types that
you support.