ipv4: rename ip_options_echo to __ip_options_echo()

ip_options_echo() assumes struct ip_options is provided in &IPCB(skb)->opt
Lets break this assumption, but provide a helper to not change all call points.

ip_send_unicast_reply() gets a new struct ip_options pointer.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc include/net/ip.h
Simple merge

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

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

diff --cc net/ipv4/tcp_ipv4.c
Simple merge