This adds the required code changes and minimal configuration to both
osmo-gbproxy.cfg and GBProxy_Tests to have osmo-gbproxy connect to two
SGSNs.
No NRI mappings are configured and hence the second SGSN isn't really
used for anything except for bringing the NS-VCs and BVCs up.
Related: OS#4472, SYS#5002
Change-Id: Ib70f7c1a29f089957f882df0e9b05ee526224611
With this setup we can and do now test:
* Paging a LAI on BVC0 is sent once per matching NSE
* Paging a LAI on BVC0 is sent to multiple different matching NSE
* Paging a RA ID on BVC0 is sent once per matching NSE
* Paging a RA ID on BVC0 is sent to multiple different matching NSE
Change-Id: I698a932b3dc78c776e9350283109463bcdc40e6b
Related: SYS#5226