Add local GNU Makefile and Windows nmake Makefile for kyber768

I shouldve run `make -B test-all`.

This has the downside of not supporting running tests on Valgrind, see
the discussion in issue #15. However, this does test quite a lot
already.

This uses the docker container defined in
https://github.com/thomwiggers/debian-unstable-powerpc/.

Co-authored-by: Thom Wiggers <thom@thomwiggers.nl>

See #2

We moved to SHA256 for compatibility with older versions of Python 3, and this hash is thus unchecked. It will only get out of date, so it seems better to remove it.

Closes #11

It's already available. Should speed up the build a small bit

It's poorly supported and reports false positives (See also #10)

Otherwise Make is vague if it did anything

We need to use find loops to exclude *.dSYM folders created by -g on
OSX.

This is a poor mans fix for the problem with the build, but what can you do 🤷