res_statsd.c: Made use defaults if the statsd.conf file does not exist.

This module is an optional dependency of many modules.  If it declines to
load it then forces other modules that can optionally use this module to
also decline.

* Made use default configuration if there is a config error or the config
file does not exist.

Change-Id: If1068a582ec54ab7fb437265cb5370a97a825737