nat: Rename "struct sccp_connections" to "struct nat_sccp_connection"

The name sccp_connection is used in the osmo-sccp code, sccp_connections
was used in the NAT for tracking a sccp_connection. Rename it so it is
obvious that the struct belongs to the nat.

The rename was done with sed:
$ sed -i s,"struct sccp_connections","struct nat_sccp_connection",g \
		include/openbsc/*.h src/osmo-bsc_nat/* tests/*/*
diff --git a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
index 85f940b..701cc72 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
@@ -108,7 +108,7 @@
 	return con->_endpoint_status == NULL;
 }
 
-static int bsc_assign_endpoint(struct bsc_connection *bsc, struct sccp_connections *con)
+static int bsc_assign_endpoint(struct bsc_connection *bsc, struct nat_sccp_connection *con)
 {
 	int multiplex;
 	int timeslot;
@@ -165,9 +165,9 @@
 	return (multiplex << 5) | (timeslot & 0x1f);
 }
 
-int bsc_mgcp_assign_patch(struct sccp_connections *con, struct msgb *msg)
+int bsc_mgcp_assign_patch(struct nat_sccp_connection *con, struct msgb *msg)
 {
-	struct sccp_connections *mcon;
+	struct nat_sccp_connection *mcon;
 	struct tlv_parsed tp;
 	uint16_t cic;
 	uint8_t timeslot;
@@ -299,7 +299,7 @@
 	bsc_write_mgcp(bsc, (uint8_t *) buf, len);
 }
 
-void bsc_mgcp_init(struct sccp_connections *con)
+void bsc_mgcp_init(struct nat_sccp_connection *con)
 {
 	con->msc_endp = -1;
 	con->bsc_endp = -1;
@@ -310,7 +310,7 @@
  * once the internal DLCX response arrives this can be combined with the
  * the BSC side and forwarded as a trap.
  */
-static void remember_pending_dlcx(struct sccp_connections *con, uint32_t transaction)
+static void remember_pending_dlcx(struct nat_sccp_connection *con, uint32_t transaction)
 {
 	struct bsc_nat_call_stats *stats;
 	struct bsc_connection *bsc = con->bsc;
@@ -366,7 +366,7 @@
 	llist_add_tail(&stats->entry, &bsc->pending_dlcx);
 }
 
-void bsc_mgcp_dlcx(struct sccp_connections *con)
+void bsc_mgcp_dlcx(struct nat_sccp_connection *con)
 {
 	/* send a DLCX down the stream */
 	if (con->bsc_endp != -1 && con->bsc->_endpoint_status) {
@@ -475,10 +475,10 @@
 }
 
 
-struct sccp_connections *bsc_mgcp_find_con(struct bsc_nat *nat, int endpoint)
+struct nat_sccp_connection *bsc_mgcp_find_con(struct bsc_nat *nat, int endpoint)
 {
-	struct sccp_connections *con = NULL;
-	struct sccp_connections *sccp;
+	struct nat_sccp_connection *con = NULL;
+	struct nat_sccp_connection *sccp;
 
 	llist_for_each_entry(sccp, &nat->sccp_connections, list_entry) {
 		if (sccp->msc_endp == -1)
@@ -501,7 +501,7 @@
 {
 	struct bsc_nat *nat;
 	struct bsc_endpoint *bsc_endp;
-	struct sccp_connections *sccp;
+	struct nat_sccp_connection *sccp;
 	struct mgcp_endpoint *mgcp_endp;
 	struct msgb *bsc_msg;
 
@@ -590,7 +590,7 @@
 
 	/* if a CRCX failed... send a DLCX down the stream */
 	if (bsc_endp->transaction_state == MGCP_ENDP_CRCX) {
-		struct sccp_connections *con;
+		struct nat_sccp_connection *con;
 		con = bsc_mgcp_find_con(bsc->nat, ENDPOINT_NUMBER(endp));
 		if (!con) {
 			LOGP(DMGCP, LOGL_ERROR,