x86_64 is used as a baseline: the "x86_64" entry, whatever status it has,
is transformed into "all", and then the other entries in ARCHITECTURES
either dropped or rearranged appropriately.
Yes, the website is now "xpdfreader", but the Linux packages are still
called "xpdf", and as you can see it provides all the same commands
(and then some) that the xpdf package does.