fix segfault from freeaddrinfo on hints

We were receiving segfaults regularly on reload, and I finally tracked it down to [this line](https://github.com/jib/libvmod-statsd/blob/master/src/vmod_statsd.c#L184).  A coworker, [Jason](https://github.com/jasonmoo), figured it had something to do with the fact that the hints' addrinfo struct wasn't complete (and doesn't need to be) and therefore who knows what's going on in `freeaddrinfo()`, but it wasn't happy.  So we zeroed out hints (doesn't seem to matter where - anywhere between the `malloc()` and `freeaddrinfo()` works) and sure enough, the segfaults stopped.