Currently, SourceForge is down and downloads give a 500 error. That's
not overly uncommon (even less often the case these days). Fortunately,
zlib provides another mirror on their homepage, add that as option to
the package description. (https://www.zlib.net/)
Also fix test-packages: it was saving the output from CT_DoLog into
the checksum file. Also use one file per version.
Signed-off-by: Alexey Neyman <stilor@att.net>
