`benchmark/dgram/bind-params` exits with an error frequently in its
current form because no error handler is applied. Add no-op error
handlers to avoid the problem.

```console
$ node benchmark/run.js --filter bind-params dgram

dgram/bind-params.js
dgram/bind-params.js address="true" port="true" n=10000:
193,347.42178656923
events.js:182
      throw er; // Unhandled 'error' event
      ^

Error: bind ENFILE 0.0.0.0
    at Object._errnoException (util.js:1041:11)
    at _exceptionWithHostPort (util.js:1064:20)
    at _handle.lookup (dgram.js:242:18)
    at _combinedTickCallback (internal/process/next_tick.js:141:11)
    at process._tickCallback (internal/process/next_tick.js:180:9)
    at Function.Module.runMain (module.js:611:11)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:598:3
$
```

@Trott, feel free to drop this out if you disagree.