sprintf -> snprintf transition

Hi!

I did the changes to finally remove all users of sprintf(). It does not remove sprintf(). I leave this to Keir.

patch 1/2:
Cleanup for x86. Bound calculation was not quite correct.

patch 2/2:
ia64/ppc: The sprintf -> snprintf transition.
Warning: Due to lack of hw, these have not been compiled tested. IA64 and PPC maintainers, please verify!!

Christoph

All done. Xen is now hardened. ;-)

-- Keir