gsm_subscriber: change subscr_bsc_active_subscriber to plural

This was requested by Holger Freyther <zecke@selfish.org>.
diff --git a/openbsc/src/libmsc/gsm_subscriber.c b/openbsc/src/libmsc/gsm_subscriber.c
index f9eebc8..0889400 100644
--- a/openbsc/src/libmsc/gsm_subscriber.c
+++ b/openbsc/src/libmsc/gsm_subscriber.c
@@ -39,7 +39,7 @@
 
 void *tall_sub_req_ctx;
 
-extern struct llist_head *subscr_bsc_active_subscriber(void);
+extern struct llist_head *subscr_bsc_active_subscribers(void);
 
 int gsm48_secure_channel(struct gsm_subscriber_connection *conn, int key_seq,
                          gsm_cbfn *cb, void *cb_data);
@@ -272,7 +272,7 @@
 	struct gsm_subscriber *subscr;
 
 	/* we might have a record in memory already */
-	llist_for_each_entry(subscr, subscr_bsc_active_subscriber(), entry) {
+	llist_for_each_entry(subscr, subscr_bsc_active_subscribers(), entry) {
 		if (tmsi == subscr->tmsi)
 			return subscr_get(subscr);
 	}
@@ -286,7 +286,7 @@
 {
 	struct gsm_subscriber *subscr;
 
-	llist_for_each_entry(subscr, subscr_bsc_active_subscriber(), entry) {
+	llist_for_each_entry(subscr, subscr_bsc_active_subscribers(), entry) {
 		if (strcmp(subscr->imsi, imsi) == 0)
 			return subscr_get(subscr);
 	}
@@ -299,7 +299,7 @@
 {
 	struct gsm_subscriber *subscr;
 
-	llist_for_each_entry(subscr, subscr_bsc_active_subscriber(), entry) {
+	llist_for_each_entry(subscr, subscr_bsc_active_subscribers(), entry) {
 		if (strcmp(subscr->extension, ext) == 0)
 			return subscr_get(subscr);
 	}
@@ -314,7 +314,7 @@
 	char buf[32];
 	sprintf(buf, "%llu", id);
 
-	llist_for_each_entry(subscr, subscr_bsc_active_subscriber(), entry) {
+	llist_for_each_entry(subscr, subscr_bsc_active_subscribers(), entry) {
 		if (subscr->id == id)
 			return subscr_get(subscr);
 	}