tcp: expose the tcp_mark_push() and tcp_skb_entail() helpers
the tcp_skb_entail() helper is actually skb_entail(), renamed
to provide proper scope.
The two helper will be used by the next patch.
RFC -> v1:
- rename skb_entail to tcp_skb_entail (Eric)
Acked-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>