rename gsm_subscriber_connection to ran_conn

In preparation for inter-BSC and inter-MSC handover, we need to separate the
subscriber management logic from the actual RAN connections. What better time
to finally rename gsm_subscriber_connection.

* Name choice:

In 2G, this is a connection to the BSS, but even though 3GPP TS commonly talk
of "BSS-A" and "BSS-B" when explaining handover, it's not good to call it
"bss_conn": in 3G a BSS is called RNS, IIUC.

The overall term for 2G (GERAN) and 3G (UTRAN) is RAN: Radio Access Network.

* Rationale:

A subscriber in the MSC so far has only one RAN connection, but e.g. for
inter-BSC handover, a second one needs to be created to handover to. Most of
the items in the former gsm_subscriber_connection are actually related to the
RAN, with only a few MM and RTP related items. So, as a first step, just rename
it to ran_conn, to cosmetically prepare for moving the not strictly RAN related
items away later.

Also:

- Rename some functions from msc_subscr_conn_* to ran_conn_*
- Rename "Subscr_Conn" FSM instance name to "RAN_conn"
- Rename SUBSCR_CONN_* to RAN_CONN_*

Change-Id: Ic595f7a558d3553c067f77dc67543ab59659707a
diff --git a/include/osmocom/msc/silent_call.h b/include/osmocom/msc/silent_call.h
index 5fec77b..70324e5 100644
--- a/include/osmocom/msc/silent_call.h
+++ b/include/osmocom/msc/silent_call.h
@@ -1,15 +1,15 @@
 #ifndef _SILENT_CALL_H
 #define _SILENT_CALL_H
 
-struct gsm_subscriber_connection;
+struct ran_conn;
 
 extern int gsm_silent_call_start(struct vlr_subscr *vsub,
                                  void *data, int type);
 extern int gsm_silent_call_stop(struct vlr_subscr *vsub);
 
 #if 0
-extern int silent_call_rx(struct gsm_subscriber_connection *conn, struct msgb *msg);
-extern int silent_call_reroute(struct gsm_subscriber_connection *conn, struct msgb *msg);
+extern int silent_call_rx(struct ran_conn *conn, struct msgb *msg);
+extern int silent_call_reroute(struct ran_conn *conn, struct msgb *msg);
 #endif
 
 #endif /* _SILENT_CALL_H */