netcat: add forced dependence on BusyBox

netcat: add forced dependence on BusyBox

It may be necessary if packages become built in parallel, leading to a
race condition on the creation of the "nc" link.

Of course this still leaves a race conditon if other netcat competitors
but we must assume thet the user is a grown-up person who knows what is
doing.

Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
[Arnout: Don't force-remove the existing nc, not needed according to
         Romain.]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>