Fix a corner case in receiving UDP data

CL: none

PUBLISHED_FROM=9c13882517374644c6d799976f1048f04ae446d7

mongoose.c

@@ -2834,7 +2834,6 @@ void mg_if_recv_udp_cb(struct mg_connection *nc, void *buf, int len,
   } else {
     /* Drop on the floor. */
     MG_FREE(buf);
-    nc->iface->vtable->recved(nc, len);
   }
 }