fix: rt_kprintf隐式声明导致的日志异常

[meng-plus]

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

iar8.40 中组件仅调用rtdbg.h做日志重定向，出现rt_kprintf隐式声明导致%f打印日志出现错误

# with_proto.c
extern int rt_kprintf(const char *fmt, ...);
float g_f = 1.5f;  int g_i = 7;
void call_site(void) { rt_kprintf("%d %f\n", g_i, g_f); }

# no_proto.c（去掉 extern 声明 = 隐式声明）
float g_f = 1.5f;  int g_i = 7;
void call_site(void) { rt_kprintf("%d %f\n", g_i, g_f); }

你的解决方案是什么 (what is your solution)

补全头文件

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

• BSP:

• .config:

• action:

]

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've 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
• 没有垃圾代码，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've 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clang-format 源码格式化工具确保格式符合RT-Thread代码规范 This PR has been formatted with clang-format and complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/ALL_BSP_COMPILE.json 详细请参考链接BSP自查

[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).

---

🛠 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

• Use workflow from 保持默认分支（通常为 master）
  Keep the default branch (usually master) in Use workflow from
• 在 branch 输入框填写 PR 分支 patch-1
  Enter PR branch patch-1 in the branch field
• 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 "/")

3. 等待工作流完成 | Wait for the workflow to complete
   格式化后的代码将作为独立提交推送至你的分支。
   The formatting changes will be pushed to your branch as a separate commit.

完成后，提交将自动更新至 patch-1 分支，关联的 Pull Request 也会同步更新。
Once completed, commits will be pushed to the patch-1 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]

MemBrowse Memory Report

No memory changes detected for:

• at32f415-start
• esp32-c3
• gd32105r-start
• hc32f334
• hpmicro-hpm5301evklite
• infineon-psoc6
• k230
• loongson-ls1cdev
• nordic-nrf51822
• nuvoton-m487
• nxp-lpc1114
• qemu-virt64-aarch64
• raspberry-pico-rp2040
• renesas-ra2l1
• simulator
• stm32f407-rt-spark
• stm32l475-atk-pandora-llvm
• wch-ch32v208w-r0
• x86
• xuantie-e901plus

[Rbb666]

尚未在 IAR 8.40 上验证原报告的浮点日志异常。建议作者补齐 PR 中的 BSP、.config，并提供同配置下修改前后 %d %f 的实际输出记录。

[mysterywolf]

直接include rtthread.h可能会导致递归引用的问题，也就是rtthread.h在哪里include了rtdbg.h 然后rtdbg.h又include rtthread.h 成环了。看看可否include rtklibc.h