klibc: fix tiny vsnprintf long long formatting

[CYFS3]

拉取/合并请求描述（PR description）

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为什么提交这份PR (why to submit this PR)

修复 issue #11596：tiny 版本 rt_vsnprintf 在格式化 %lld/%lli 时，把 ll qualifier 与 l qualifier 合并到 long 路径处理，导致 long long 数值被错误截断或符号判断错误，例如 INT64_MAX 输出为 -1。

你的解决方案是什么 (what is your solution)

在 rt_vsnprintf_tiny.c 中将 L（内部用于表示 ll）和 l 的有符号处理拆开：ll 按 long long 取参并按 64 位符号范围处理，l 继续保持 long 路径。同步补充 rt_sprintf long long 边界值回归用例，覆盖 INT32_MIN、UINT32_MAX、INT64_MIN、INT64_MAX。

请提供验证的bsp和config (provide the config and bsp)

• BSP: bsp/qemu-vexpress-a9

• .config: CONFIG_RT_KLIBC_USING_VSNPRINTF_LONGLONG=y，未启用 CONFIG_RT_KLIBC_USING_VSNPRINTF_STANDARD，使用 tiny 版本验证

• action: 本地环境缺少可用交叉编译工具链，未触发 action；已执行 git diff --check

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当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I have considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有冗余代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I have commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用formatting等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification
• 如果是新增BSP，已经添加ci检查到 ALL_BSP_COMPILE.json

[github-actions]

👋 感谢您对 RT-Thread 的贡献！Thank you for your contribution to RT-Thread!

为确保代码符合 RT-Thread 的编码规范，请在你的仓库中执行以下步骤运行代码格式化工作流（如果格式化CI运行失败）。
To ensure your code complies with RT-Thread's coding style, please run the code formatting workflow by following the steps below (If the formatting of CI fails to run).

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🛠 操作步骤 | Steps

1. 前往 Actions 页面 | Go to the Actions page
   点击进入工作流 → | Click to open workflow →

2. 点击 Run workflow | Click Run workflow

• 设置需排除的文件/目录（目录请以"/"结尾）
  Set files/directories to exclude (directories should end with "/")
• 将目标分支设置为 \ Set the target branch to：fix/klibc-vsnprintf-long-long
• 设置PR number为 \ Set the PR number to：11600

3. 等待工作流完成 | Wait for the workflow to complete
   格式化后的代码将自动推送至你的分支。
   The formatted code will be automatically pushed to your branch.

完成后，提交将自动更新至 fix/klibc-vsnprintf-long-long 分支，关联的 Pull Request 也会同步更新。
Once completed, commits will be pushed to the fix/klibc-vsnprintf-long-long branch automatically, and the related Pull Request will be updated.

如有问题欢迎联系我们，再次感谢您的贡献！💐
If you have any questions, feel free to reach out. Thanks again for your contribution!

[github-actions]

📌 Code Review Assignment

🏷️ Tag: kernel

Reviewers: @GorrayLi @ReviewSun @hamburger-os @lianux-mm @wdfk-prog @xu18838022837

Changed Files (Click to expand)

• src/klibc/rt_vsnprintf_tiny.c
• src/klibc/utest/TC_rt_sprintf.c

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📊 Current Review Status (Last Updated: 2026-07-09 13:16 CST)

• ⌛ @GorrayLi Pending Review
• ⌛ @ReviewSun Pending Review
• ⌛ @hamburger-os Pending Review
• ⌛ @lianux-mm Pending Review
• ⌛ @wdfk-prog Pending Review
• ⌛ @xu18838022837 Pending Review

---

📝 Review Instructions

1. 维护者可以通过单击此处来刷新审查状态: 🔄 刷新状态
   Maintainers can refresh the review status by clicking here: 🔄 Refresh Status

2. 确认审核通过后评论 LGTM/lgtm
   Comment LGTM/lgtm after confirming approval

3. PR合并前需至少一位维护者确认
   PR must be confirmed by at least one maintainer before merging

ℹ️ 刷新CI状态操作需要具备仓库写入权限。
ℹ️ Refresh CI status operation requires repository Write permission.

[github-actions]

MemBrowse Memory Report

No memory changes detected for:

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