distrib: Integrate path record computation into distrib layer

The patch includes:
- A new global struct is created. The struct includes preloaded
  smdb database and Access Layer context. The context holds
  internal data index used for boost path record computation.
- Call for "half world" algorithm

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>