examples/vhost: import userspace vhost application

examples/vhost: import userspace vhost application

The vhost sample application demonstrates integration of the Intel(R) Data Plane
Development Kit (Intel(R) DPDK) with the Linux KVM hypervisor by implementing the
vhost-net offload API. The sample application performs simple packet switching
between virtual machines based on Media Access Control (MAC) address or Virtual
Local Area Network (VLAN) tag. The splitting of ethernet traffic from an external switch
is performed in hardware by the Virtual Machine Device Queues (VMDQ) and Data
Center Bridging (DCB) features of the Intel(R) 82599 10 Gigabit Ethernet Controller.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>