datapath-windows: Add file NetlinkError.h.

datapath-windows: Add file NetlinkError.h.

Contains error codes for netlink transactional errors.
These errors are passed to the "error" field (INT) of the NL_MSG_ERR struct.
The userspace requires them to be negative values: the nl_msg_nlmsgerr userspace
function transforms them from negative to positive values.

These error codes correspond to the userspace error codes defined in:
"C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\include\errno.h"

Signed-off-by: Samuel Ghinet <sghinet@cloudbasesolutions.com>
Acked-by: Eitan Eliahu <eliahue@vmware.com>
Acked-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>