revert and fix parse cmdline bug

[waruqi]

cmdline 这块解析之前还能正常跑，新版本直接获取到一串非截断乱码。

while (len > 0 && (buf[len - 1] <= 0 || buf[len - 1] == 10 || buf[len - 1] == 13)) --len;

问题1： 为啥要改成尾遍历，如果 X 是无效字符，abd X edf XXXX 中间如果出现部分有效字符，这样获取的 len 就是有问题的，得从 0 开始遍历才对。

return new String(buf, StandardCharsets.US_ASCII);

问题2： 最后那个 len 算完，也没用进去哈。。。

[tencent-adm]

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