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/mncc_call.c b/src/libmsc/mncc_call.c
index 5ca91d0..34c7299 100644
--- a/src/libmsc/mncc_call.c
+++ b/src/libmsc/mncc_call.c
@@ -256,7 +256,7 @@
 		return true;
 	}
 
-	if (!osmo_sockaddr_str_is_set(&mncc_call->rtps->local)) {
+	if (!osmo_sockaddr_str_is_nonzero(&mncc_call->rtps->local)) {
 		LOG_MNCC_CALL(mncc_call, LOGL_DEBUG, "Got RTP_CREATE, but RTP stream has no local address\n");
 		return true;
 	}
@@ -294,7 +294,7 @@
 
 static bool mncc_call_tx_rtp_create(struct mncc_call *mncc_call)
 {
-	if (!mncc_call->rtps || !osmo_sockaddr_str_is_set(&mncc_call->rtps->local)) {
+	if (!mncc_call->rtps || !osmo_sockaddr_str_is_nonzero(&mncc_call->rtps->local)) {
 		mncc_call_error(mncc_call, "Cannot send RTP_CREATE, no local RTP address set up\n");
 		return false;
 	}