Qt: rtpstream_id memleak

Free fwd_id and rev_id, not just their members, if they aren't used.
Coverity CID 1512428

ui/qt/wireshark_main_window.cpp

@@ -3129,9 +3129,11 @@ QString WiresharkMainWindow::findRtpStreams(QVector<rtpstream_id_t *> *stream_id
     //
     if (!fwd_id_used) {
         rtpstream_id_free(fwd_id);
+        g_free(fwd_id);
     }
     if (!rev_id_used) {
         rtpstream_id_free(rev_id);
+        g_free(rev_id);
     }
     return NULL;
 }