[arch-dev-public] adding pyelftools to [extra]

Hello, I'd like to add pyelftools (http://pypi.python.org/pypi/pyelftools) to [extra]. The goal is to replace various utilities that are currently used by namcap to analyse ELF files, notably prelink. Then I would apply Dave's patch for namcap (http://mailman.archlinux.org/pipermail/arch-projects/2012-February/002448.ht...) that uses it and drop dependency on prelink. Rémy.