bts: Add TC_pcu_rr_suspend() to test forwarding of RR SUSPEND via PCU socket

This test opens a SDCCH and sends a RR SUSPEND message from the
simulated MS.  It then expects the BTS to pick that up and forward
it to the PCU socket rather than via RSL to the BSC.

Change-Id: I4da6e9d7c5dfbd0e017d2a63c6474da700c38e52
Related: OS#2249
Related: OS#4023
2 files changed