unix: call setgoups before calling setuid/setgid

Partial fix for #1093
static void uv__process_close_stream(uv_stdio_container_t* container) {
  if (!(container->flags & UV_CREATE_PIPE)) return;
  uv__stream_close((uv_stream_t*)container->data.stream);
}

static void uv__process_close_stream(uv_stdio_container_t* container) {
  if (!(container->flags & UV_CREATE_PIPE)) return;
  uv__stream_close((uv_stream_t*)container->data.stream);
}
