When you add a new use flag that pulls in a binary only package for a
particular arch, please mask that useflag on all arches that cannot
support it (or create a bug to get it done before the new use flag is
introduced into the live tree).
As a side note, all non-x86 arches will want to mask fdftk as it's now in
use by the ~arch versions of php and mod_php.
Gentoo/Sparc Team Co-Lead