sit: Setup and TX path for sit/UDP foo-over-udp encapsulation
sit: Setup and TX path for sit/UDP foo-over-udp encapsulation

Added netlink handling of IP tunnel encapulation paramters, properly
adjust MTU for encapsulation. Added ip_tunnel_encap call to
ipip6_tunnel_xmit to actually perform FOU encapsulation.

Signed-off-by: Tom Herbert <0786393240831fc3b5d6ed63658cfb1f3b1e6c40@google.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs