What used to be `tools/emul/user.h` was in fact specific to zasm, so I
moved it there.
To avoid name confusion, I renamed what used to be kernel.h and user.h
to kernel-bin.h and user-bin.h.
This allows us to break through the 64K limit for includes CFS in zasm,
a limit we were dangerously close to breaking. In fact, this commit
makes us go over that limit. Right in time!
