[arm_compiler_v4/v5] define rt_packed as __packed

[cmbjxxiao]

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

使用MDK5编译器编译工程后，在运行find_valid_gpt函数时， 因sizeof (legacy_mbr)得出的长度未按1字节对齐而出现内存覆盖问题

你的解决方案是什么 (what is your solution)

1、当 __ARMCC_VERSION < 6010050 时定义 rt_packed 为 __packed
2、参考文档:
1）ARM Compiler toolchain Using the Compiler Version 5.01
https://developer.arm.com/documentation/dui0472/g/compiler-coding-practices/the---packed-qualifier-and-unaligned-data-access-in-c-and-c---code?lang=en
2）ARM Compiler toolchain Using the Compiler Version 4.1
https://developer.arm.com/documentation/dui0472/c/compiler-coding-practices/the---packed-qualifier-and-unaligned-data-access-in-c-and-c---code?lang=en
3）ARM Software Development Toolkit Reference Guide Version 2.50
https://developer.arm.com/documentation/dui0041/c/ARM-Compiler-Reference/Compiler-specific-features/Type-qualifiers?lang=en

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

• BSP:bsp\hc32\ev_hc32f4a0_lqfp176

-.config:CONFIG_RT_USING_DFS=y,CONFIG_RT_USING_BLK=y,CONFIG_RT_BLK_PARTITION_EFI=y,CONFIG_BSP_USING_SDIO=y,CONFIG_BSP_USING_SDIO1=y

• action:https://github.com/cmbjxxiao/rt-thread/actions/runs/16517125437

]

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.github/workflows/bsp_buildings.yml 详细请参考链接BSP自查

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[github-actions]

📌 Code Review Assignment

🏷️ Tag: bsp_hc32

Reviewers: @levizh

Changed Files (Click to expand)

• bsp/hc32/tools/sdk_dist.py

🏷️ Tag: components

Reviewers: @Maihuanyi

Changed Files (Click to expand)

• components/drivers/block/partitions/efi.h
• components/drivers/include/drivers/nvme.h

---

📊 Current Review Status (Last Updated: 2025-07-25 16:11 CST)

• ⌛ @Maihuanyi Pending Review
• ⌛ @levizh Pending Review

---

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   Comment LGTM/lgtm after confirming approval

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