Implement IuCS (large refactoring and addition)

osmo-nitb becomes osmo-msc
add DIUCS debug log constant
add iucs.[hc]
add msc vty, remove nitb vty
add libiudummy, to avoid linking Iu deps in tests
Use new msc_tx_dtap() instead of gsm0808_submit_dtap()
libmgcp: add mgcpgw client API
bridge calls via mgcpgw

Enable MSC specific CTRL commands, bsc_base_ctrl_cmds_install() still needs to
be split up.

Change-Id: I5b5b6a9678b458affa86800afb1ec726e66eed88
diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c
index 071dd97..18625ae 100644
--- a/src/gprs/gprs_sgsn.c
+++ b/src/gprs/gprs_sgsn.c
@@ -247,6 +247,7 @@
 
 	ctx->ran_type = MM_CTX_T_UTRAN_Iu;
 	ctx->iu.ue_ctx = uectx;
+	ctx->iu.ue_ctx->rab_assign_addr_enc = sgsn->cfg.iu.rab_assign_addr_enc;
 	ctx->iu.new_key = 1;
 	ctx->gmm_state = GMM_DEREGISTERED;
 	ctx->pmm_state = PMM_DETACHED;