We need to process cluster workers before any preload modules is
executed. Otherwise, the child processes are not correctly disovered
as clustered workers inside the preloaded modules.
Fixes: https://github.com/iojs/io.js/issues/1269
PR-URL: https://github.com/iojs/io.js/pull/1314
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Fedor Indutny <fedor@indutny.com>
