Initial support for FreeBSD platform:
 - build system modifications (SConscripts)

Change-Id: Ibf2240267aed7a5fffbdc8b2a99afe070d1d6516
Authors: Grzegorz Bernacki, Michał Dubiel, Dominik Ermel
Merge remote-tracking branch 'juniper/master' into review-rebased

Conflicts:
	src/vnsw/agent/contrail/SConscript

Change-Id: I379ddbdb04f058d880e27ac3255d9f9ad6775f98