> * Why is pkgtools/x11-links built automatically?  It seems this should
  ...
  >   this wouldn't hurt someone doing things right, but still if I try to
  >   build only a package that doesn't use x, I shouldn't have this
  >   built.

  It should not be installed automatically. What package(s) were you
  building when this happened?

None - it was in the makeroot stage.  In pkg_comp, see makeroot_x11(),
called unconditionally from makeroot(), which builds the pkg if the
chroot has x sets.

  >  (Same for digest, but I see there is an issue with compiler
  >   bootstrapping.)

  digest is required for checking checksums.

Sure, but doesn't pkgsrc build it when it needs it?