test: retry on smartos if ECONNREFUSED

SmartOS has a bug that causes unexpected ECONNREFUSED errors.

See https://smartos.org/bugview/OS-2767

If ECONNREFUSED on SmartOS, retry the test one time.

Fixes: https://github.com/nodejs/node/issues/3864
Fixes: https://github.com/nodejs/node/issues/2815
PR-URL: https://github.com/nodejs/node/pull/3941


Reviewed-By: Fedor Indutny <fedor@indutny.com>