Support for VRF translation nexthops (also known as table nexthops)

A vrf translation nexthop changes the vrf of the packet and forwards
the packet in the new vrf. In the VCPE use case, packets that arrive
from the uplink and those that need to be forwarded to one of the other
physical ports, should be subjected to VRF translation before
forwarding. In this case, a label will point to the translation nexthop.

Also,

Fix compilation warnings for utils/ by making a declarion in vr_interface.h
inside __KERNEL__

Make Scons compile the kernel module always, thus making 'make' do the
decision to build the module or not

Closes-Bug:#1386573
Change-Id: Ibba85eec0edddf34c041c4237cb2b5f93f3d4e67
closes-bug:#1386707 Trapping the ARP response to Agent if route is marked with ARP_TRAP flag

Change-Id: Id344ad9e1d78c1580114996cd8cbfe4a0ba27153
Classify untagged packets into a native vlan

In VCPE case, each bare metal server that is connected behind a port is
treated as a VM. Since we are modeling the interface as a vlan interface,
untagged packets should be marked as the property of a native vlan.

Add a new flag to the vif that will decide whether untagged packets should
be clasified to native vlan or not

Change-Id: I5d0f8cf3fc011a8ed74c0187974a088999be6531
Closes-BUG:#1387521
Merge "closes-bug:#1386707 Trapping the ARP response to Agent if route is marked with ARP_TRAP flag"
closes-bug:#1386174 Tagging the packet to Virtual vlan interface with
vlan tag and removing the vlan tag while foarwarding to fabric nh for Vmware
Change-Id: Ic3c74fdad5ddc3713a7643af215bd010df3fec18
Fix IPv6 neighbor discovery if VLAN is present

Issue was reported in ESXi interop and has been verified in the same environment

Change-Id: I3fc69c591919749c0af3506446ac0a747a43ff53