Merge branch 'tcp-fastopen-ipv6'

Yuchung Cheng says:

====================
tcp: IPv6 support for fastopen server

This patch series add IPv6 support for fastopen server. To minimize
code duplication in IPv4 and IPv6, the current v4 only code is
refactored and common code is moved into net/ipv4/tcp_fastopen.c.

Also the current code uses a different function from
tcp_v4_send_synack() to send the first SYN-ACK in fastopen.
The new code eliminates this separate function by refactoring the
child-socket and syn-ack creation code.  After these refactoring
in the first four patches, we can easily add the fastopen code in
IPv6 by changing corresponding IPv6 functions.

Note Fast Open client already supports IPv6. This patch is for
the server-side (passive open) IPv6 support only.
====================

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