unix: call setgoups before calling setuid/setgid

Partial fix for #1093
int uv_process_kill(uv_process_t* process, int signum) {
  return uv_kill(process->pid, signum);
}

int uv_process_kill(uv_process_t* process, int signum) {
  return uv_kill(process->pid, signum);
}
