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/osmo-bsc/osmo_bsc_msc.c b/openbsc/src/osmo-bsc/osmo_bsc_msc.c
index 8b7c6e2..b4feded 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_msc.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_msc.c
@@ -306,7 +306,7 @@
 	msc_ping_timeout_cb(data);
 
 	sig.data = data;
-	dispatch_signal(SS_MSC, S_MSC_CONNECTED, &sig);
+	osmo_signal_dispatch(SS_MSC, S_MSC_CONNECTED, &sig);
 }
 
 /*
@@ -325,7 +325,7 @@
 	osmo_timer_del(&data->pong_timer);
 
 	sig.data = data;
-	dispatch_signal(SS_MSC, S_MSC_LOST, &sig);
+	osmo_signal_dispatch(SS_MSC, S_MSC_LOST, &sig);
 
 	msc->is_authenticated = 0;
 	bsc_msc_schedule_connect(msc);