compiler warning: fix

        cur_pos = slash_pos + 1; /* jump to the rest of the string */

        if(++ftpc->dirdepth >= ftpc->diralloc) {

          /* enlarge array */

          char *bigger;

          char **bigger;

          ftpc->diralloc *= 2; /* double the size each time */

          bigger = realloc(ftpc->dirs, ftpc->diralloc * sizeof(ftpc->dirs[0]));

          if(!bigger) {

            freedirs(ftpc);

            return CURLE_OUT_OF_MEMORY;

          }

          ftpc->dirs = (char **)bigger;

          ftpc->dirs = bigger;

        }

      }

    }