Move the tcp receive probes around so that we see all packets. Also make
sure to restore the length in the IP header after zeroing out part of
the header for the TCP checksum.
Merge branch '20130428-tcp-provider' into markj-develop
Set the IPv6 payload length in the TCP code so that the ipinfo_t plength
isn't bogus for tcp:::send. It'll be incorrect since it doesn't include
the option headers, but oh well.
The plength is supposed to include the header size.
Merge branch '20130428-tcp-provider' into markj-develop