Fix an unused-variable warning

check_private_dir(const char *dirname, cpd_check_t check,

                  const char *effective_user)

{

  int fd;

  int r;

  struct stat st;

  tor_assert(dirname);

#ifndef _WIN32

  int fd;

  unsigned unwanted_bits = 0;

  const struct passwd *pw = NULL;

  uid_t running_uid;