ASCI: Add simple implementation of Group Call Register

This is a built-in data structure to store and handle voice group calls.

The GCR will be used by VGCS/VBS call control.
 (Chg-Id: I9947403fde8212b66758104443c60aaacc8b1e7b)

The GCR will be used by VTY code.
 (Chg-Id: I5bd034a62fc8b483f550d29103c2f7587198f590)

Change-Id: Ia74a4a865f943c5fb388cd28f9406005c92e663e
Related: OS#4854
diff --git a/src/libmsc/msc_net_init.c b/src/libmsc/msc_net_init.c
index 45500b2..f63acf8 100644
--- a/src/libmsc/msc_net_init.c
+++ b/src/libmsc/msc_net_init.c
@@ -75,6 +75,7 @@
 	INIT_LLIST_HEAD(&net->trans_list);
 	INIT_LLIST_HEAD(&net->upqueue);
 	INIT_LLIST_HEAD(&net->neighbor_ident_list);
+	INIT_LLIST_HEAD(&net->asci.gcr_lists);
 
 	/* init statistics */
 	net->msc_ctrs = rate_ctr_group_alloc(net, &msc_ctrg_desc, 0);