use osmo_sockaddr_str_is_nonzero()

Also regard an RTP port as invalid if the IP address is 0.0.0.0.
Achieve this by using osmo_sockaddr_str_is_nonzero() instead of
osmo_sockaddr_str_is_set().

Depends: I73cbcab90cffcdc9a5f8d5281c57c1f87b2c3550 (libosmocore)
Change-Id: I53ddb19a70fda3deb906464e1b89c12d9b4c7cbd
diff --git a/src/libmsc/call_leg.c b/src/libmsc/call_leg.c
index 794eda2..b1d0b1e 100644
--- a/src/libmsc/call_leg.c
+++ b/src/libmsc/call_leg.c
@@ -301,7 +301,7 @@
 	rtps = cl->rtp[dir];
 	if (!rtps)
 		return NULL;
-	if (!osmo_sockaddr_str_is_set(&rtps->local))
+	if (!osmo_sockaddr_str_is_nonzero(&rtps->local))
 		return NULL;
 	return &rtps->local;
 }
@@ -327,7 +327,7 @@
 	}
 	if (codec_if_known)
 		rtp_stream_set_codec(cl->rtp[dir], *codec_if_known);
-	if (remote_addr_if_known && osmo_sockaddr_str_is_set(remote_addr_if_known))
+	if (remote_addr_if_known && osmo_sockaddr_str_is_nonzero(remote_addr_if_known))
 		rtp_stream_set_remote_addr(cl->rtp[dir], remote_addr_if_known);
 	return rtp_stream_ensure_ci(cl->rtp[dir], cl->mgw_endpoint);
 }