Merge branch 'hyperv'

K. Y. Srinivasan says:

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Fix issues with Heper-V network offload code

WS2008 R2 does not support udp checksum offload. Furthermore, ws2012 and
ws2012 r2 have issues offloading udp checksum from Linux guests.
This patch-set addresses these issues as well as other bug fixes.
Please apply.

In this version, I have addressed the comment from David Miller with reagards
to COWing the skb prior to modifying the header (patch 3/3).
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Signed-off-by: David S. Miller <davem@davemloft.net>