Update some format placeholders.

'%td'/'%tx' means ptrdiff_t, which is more appropriate for register_t than guessing how many l's the current arch needs ('%ld', '%lld', etc.).
Drop cellspu libraries.

This fails to compile in some places, and we don't need the libraries anyway.
Merge branch 'master' of github.com:CTSRD-TESLA/TESLA

Conflicts:
	libtesla/src/iterator.c