pcu_sock: add basic pcu interface support

Adds a basic version of a pcu socket interface, similar
to the one that can be found in osmo-bts.

Change-Id: Ib13cb4099d12fa71e9e0b8727e19ab29e11909b2
diff --git a/openbsc/include/openbsc/gsm_data_shared.h b/openbsc/include/openbsc/gsm_data_shared.h
index e7c8467..3371fb9 100644
--- a/openbsc/include/openbsc/gsm_data_shared.h
+++ b/openbsc/include/openbsc/gsm_data_shared.h
@@ -869,6 +869,9 @@
 	struct amr_multirate_conf mr_full;
 	struct amr_multirate_conf mr_half;
 
+	/* PCU socket state */
+	struct pcu_sock_state *pcu_state;
+
 #endif /* ROLE_BSC */
 	void *role;
 };