ensure that Curl_wildcard_dtor() leaves WildcardData struct zero initialized

CURLcode Curl_wildcard_init(struct WildcardData *wc)

{

  DEBUGASSERT(wc->filelist == NULL);

  /* now allocate only wc->filelist, everything else

     will be allocated if it is needed. */

  wc->filelist = Curl_llist_alloc(Curl_fileinfo_dtor);

  if(wc->tmp_dtor) {

    wc->tmp_dtor(wc->tmp);

    wc->tmp_dtor = ZERO_NULL;

    wc->tmp = NULL;

  }

  DEBUGASSERT(wc->tmp == NULL);

  if(wc->filelist) {

    Curl_llist_destroy(wc->filelist, NULL);

    free(wc->pattern);

    wc->pattern = NULL;

  }

  wc->customptr = NULL;

  wc->state = CURLWC_INIT;

}