Merge branch 'tcp-tx-side-cleanups'

Eric Dumazet says:

====================
tcp: tx side cleanups

We no longer need to set skb->reserved_tailroom because
TCP sendmsg() do not put payload in skb->head anymore.

Also do some cleanups around skb->ip_summed/csum,
and CP_SKB_CB(skb)->sacked for fresh skbs.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>