src: use namespace prefix osmo_signal*

Summary of changes:

s/signal_cbfn/osmo_signal_cbfn/g
s/register_signal_handler/osmo_signal_register_handler/g
s/unregister_signal_handler/osmo_signal_unregister_handler/g
s/dispatch_signal/osmo_signal_dispatch/g
diff --git a/openbsc/src/libmsc/gsm_subscriber.c b/openbsc/src/libmsc/gsm_subscriber.c
index f0372af..f9eebc8 100644
--- a/openbsc/src/libmsc/gsm_subscriber.c
+++ b/openbsc/src/libmsc/gsm_subscriber.c
@@ -97,7 +97,7 @@
 	sig_data.bts	= conn ? conn->bts : NULL;
 	sig_data.conn	= conn;
 	sig_data.paging_result = event;
-	dispatch_signal(
+	osmo_signal_dispatch(
 		SS_PAGING,
 		event == GSM_PAGING_SUCCEEDED ?
 			S_PAGING_SUCCEEDED : S_PAGING_EXPIRED,
@@ -337,7 +337,7 @@
 			subscr_name(s), s->lac);
 		rc = db_sync_subscriber(s);
 		db_subscriber_update(s);
-		dispatch_signal(SS_SUBSCR, S_SUBSCR_ATTACHED, s);
+		osmo_signal_dispatch(SS_SUBSCR, S_SUBSCR_ATTACHED, s);
 		break;
 	case GSM_SUBSCRIBER_UPDATE_DETACHED:
 		/* Only detach if we are currently in this area */
@@ -346,7 +346,7 @@
 		LOGP(DMM, LOGL_INFO, "Subscriber %s DETACHED\n", subscr_name(s));
 		rc = db_sync_subscriber(s);
 		db_subscriber_update(s);
-		dispatch_signal(SS_SUBSCR, S_SUBSCR_DETACHED, s);
+		osmo_signal_dispatch(SS_SUBSCR, S_SUBSCR_DETACHED, s);
 		break;
 	default:
 		fprintf(stderr, "subscr_update with unknown reason: %d\n",