split subscr_con_allocate()/_free() in bsc_ and msc_

Rename current subscr_con_allocate() and subscr_con_free to bsc_*,
and add two separate msc_subscr_con_allocate() and _free().
The msc_subscr_con_free() ignores all lchan members.

In libbsc use bsc_*, in libmsc use msc_*.

Change-Id: I3cf7c7cafdf4672ec7b26058bba8a77159855257
Future: there will be distinct subscr conns for libbsc and libmsc.
diff --git a/openbsc/src/libbsc/bsc_api.c b/openbsc/src/libbsc/bsc_api.c
index 207e12a..395002a 100644
--- a/openbsc/src/libbsc/bsc_api.c
+++ b/openbsc/src/libbsc/bsc_api.c
@@ -239,7 +239,7 @@
 	return 0;
 }
 
-struct gsm_subscriber_connection *subscr_con_allocate(struct gsm_lchan *lchan)
+struct gsm_subscriber_connection *bsc_subscr_con_allocate(struct gsm_lchan *lchan)
 {
 	struct gsm_subscriber_connection *conn;
 	struct gsm_network *net = lchan->ts->trx->bts->network;
@@ -256,8 +256,7 @@
 	return conn;
 }
 
-/* TODO: move subscriber put here... */
-void subscr_con_free(struct gsm_subscriber_connection *conn)
+void bsc_subscr_con_free(struct gsm_subscriber_connection *conn)
 {
 	if (!conn)
 		return;
@@ -682,7 +681,7 @@
 	} else {
 		/* allocate a new connection */
 		rc = BSC_API_CONN_POL_REJECT;
-		lchan->conn = subscr_con_allocate(msg->lchan);
+		lchan->conn = bsc_subscr_con_allocate(msg->lchan);
 		if (!lchan->conn) {
 			lchan_release(lchan, 1, RSL_REL_NORMAL);
 			return -1;
@@ -693,7 +692,7 @@
 
 		if (rc != BSC_API_CONN_POL_ACCEPT) {
 			lchan->conn->lchan = NULL;
-			subscr_con_free(lchan->conn);
+			bsc_subscr_con_free(lchan->conn);
 			lchan_release(lchan, 1, RSL_REL_NORMAL);
 		}
 	}
@@ -852,7 +851,7 @@
 	gsm0808_clear(conn);
 
 	if (destruct)
-		subscr_con_free(conn);
+		bsc_subscr_con_free(conn);
 }
 
 static void handle_chan_ack(struct gsm_subscriber_connection *conn,