Verbatim contents of the upstream GitHub archive (Diehard4-master.zip,
commit 254ee204deebc64793123a9643c85b7d113c6c22, files dated 2019-05-21).
Imported unmodified so that every change in this fork is visible as a diff
against the original, which is what GPL-3.0 section 5(a) is asking for.
All code in this commit is obscurant's work, not mine.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>