Adds two new netperf tests, netperf_lxip_router and netperf_lwip_router
who test the TCP throughput of the NIC router when routed with a tcp-forward
rule and NAT.
Issue #2624
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082