tcp: do not fake tcp headers in tcp_send_rcvq()

Now we no longer rely on having tcp headers for skbs in receive queue,
tcp repair do not need to build fake ones.

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