The 'noux_bash.run' script has become able to present the user with an
interactive bash shell for executing various coreutils programs. It is
still pretty limited, i.e., the environment is not correctly passed to
child processes and pipes are not supported. But bash and coreutils are
operational.
This patch removes the hardcoded parent cap for the new child by
introducing a facility called 'poke' similar to copy-to-user. This
change makes the fork mechanism kernel-agnostic. The 'noux_fork'
test works on L4/Fiasco, OKL4, NOVA, Fiasco.OC, and L4ka::Pistachio.
Linux is not supported yet.
