[NETNS]: Process IP layer in the context of the correct namespace.

Replace all the rest of the init_net with a proper net on the IP layer.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc net/ipv4/ip_fragment.c
Simple merge

diff --cc net/ipv4/ip_input.c
Simple merge

diff --cc net/ipv4/ip_options.c
Simple merge

diff --cc net/ipv4/ip_output.c
Simple merge

diff --cc net/ipv4/ip_sockglue.c
Simple merge