gbproxy: Implement handling of BVC Flow Control

We must locally terminate + acknowledge any inbound BSSGP-FC-BVC,
and ourselves trigger the transmission of BSSGP-FC-BVC to each
SGSN in the pool.

Related: OS#4891
Depends: libosmcoore.git Ie59be6761177c43456898be9148727f15861a622
Change-Id: Ib6495e5de4bfcf748a98e08743d1a8f2565f8b69
1 file changed