bsc_api: The rr_cause is optional, pass it as a pointer
diff --git a/openbsc/src/bsc/osmo_bsc_api.c b/openbsc/src/bsc/osmo_bsc_api.c
index 537a9b4..f4b3148 100644
--- a/openbsc/src/bsc/osmo_bsc_api.c
+++ b/openbsc/src/bsc/osmo_bsc_api.c
@@ -45,7 +45,8 @@
 {
 }
 
-static void bsc_assign_fail(struct gsm_subscriber_connection *conn, uint32_t cause)
+static void bsc_assign_fail(struct gsm_subscriber_connection *conn,
+			    uint8_t cause, uint8_t *rr_cause)
 {
 }