RTP: print bound ports in verbose

Until now, in verbose mode was printed the dynamically selected port
pair. But the knowledge should be useful also to ensure the ports where
it doesn't need to be clear, eg. in server mode or for receiver to see
that 5004 is indeed bound.

src/rtp/rtp.c

@@ -101,6 +101,7 @@
 // IANA/RFC 6335 suggested range 49152-65535. Implementatins may differ, eg. Linux uses 32768-60999.
 #define IPPORT_DYNAMIC ((1U<<15U) + (1U<<14U))
 #define IPPORT_MAX ((1U<<16U) - 1U)
+#define MOD_NAME "[rtp] "
 
 /*
  * Encryption stuff.
@@ -1089,6 +1090,8 @@ struct rtp *rtp_init_if(const char *addr, const char *iface,
                 } else {
                         verbose_msg("Found empty UDP port pair %d/%d\n", rx_port, rx_port + 1);
                 }
+        } else {
+                MSG(VERBOSE, "Bound to ports %d/%d\n", rx_port, rx_port + 1);
         }
         if (tx_port == 0) {
                 tx_port = rx_port;