datapath-windows: fix OVS_VPORT_TYPE

The windows ovs kernel uses an OVS_VPORT_TYPE enum that is incompatible with
the userspace counterpart (enum ovs_vport_type from openvswitch.h). We must use
the same enum type for the netlink communication to work properly.

This patch makes the fix: "typedef enum ovs_vport_type OVS_VPORT_TYPE" and
changes the afferent kernel driver code:
o) vport types synthetic and emulated turn to: netdev
o) vport type internal turns to: internal
o) vport type external truns to: netdev (plus, we hold a field in vport,
"isExternal"

Signed-off-by: Samuel Ghinet <sghinet@cloudbasesolutions.com>
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
datapath-windows: Implement vport dump Netlink command.

Functionality for vport dump.
Later, when we will add more netlink dump commands, some common code will need
to be split to functions.

Notes:
a) the current implementation of vport assumes the datapath feature
"multiple upcall pids" is not used. A single upcall pid is used now.
c) the vxlan destination udp port is currently a constant. When it will become
configurable, the vport options netlink attribute will become relevant.

Signed-off-by: Samuel Ghinet <sghinet@cloudbasesolutions.com>
Acked-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
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>
datapath-windows: Add Netlink vport command get.

The transactional get vport command.
This command uses the netlink transactional errors.

Signed-off-by: Samuel Ghinet <sghinet@cloudbasesolutions.com>
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>