Include generated C files in source tarball

[edubart]

Context

To make easier to distribute sources, we should include a few generated files in the source tarball:

• machine-c-version.h
• uarch-pristine-ram.c
• uarch-pristine-hash.c

[mpolitzer]

Consider distributing those as a .patch instead.
Should make it easy for distributions to use and not complicate the source tarball generation either.