features/big-endian: a common profile for big-endian architectures and
sub-architectures.  This is for masks which are necessary due to problems which
arise solely due to endian correctness.  Solving a problem which causes one of
these masks does not guarantee that the package will automatically work on all
big-endian platforms, but it is a prerequisite to work on any of them.

Please be cautious about adding things here as it will likely affect a platform
that has not been tested on.  A good heuristic to use is either:

1) works on ppc64le and not on ppc64, or 2) work on 3 different little-endian
platforms and not on 3 different big-endian platforms, and the BE platforms
fail in the same way.