[NETFILTER]: Make unused signal code go away so nobody copies its brokenness

This code is wrong on so many levels, please lose it so it isn't
replicated anywhere else.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>