Disable IPv6 checksum computation for data packets
Disable IPv6 checksum computation for data packets

This patch disables the computation of IPv6 checksums both on receive,
since RFC 6935 allows it for tunneling protocols. It only affects the
non-raw UDP sockets (used by the non-root Android code), and allows
interoperability between Android (which enforces non-zero UDP checksums
for IPv6 by default) and Cisco IOS (which set IPv6 UDP checksums to 0
for tunneled packets, w/o a way to change this behavior).

Signed-off-by: Lorand Jakab <2e3f18b792c58c6c6b658edaba87bc89f0d6ab5a@cisco.com>

OpenOverlayRouter/oor,OpenOverlayRouter/oor,OpenOverlayRouter/oor,OpenOverlayRouter/oor,OpenOverlayRouter/oor,OpenOverlayRouter/oor,OpenOverlayRouter/oor