[src][signal]:fix the issue of inconsistent results between sigaddset and sig_mask when using musl-libc

[zhangjing0303]

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)

utest中，kernel/signal_tc.c中，rt_signal_wait_test fail.

[E/utest] [  ASSERT  ] [ unit     ] at (signal_tc.c); func: (rt_signal_wait_test:157); msg: ((recive_sig) not equal to (SIGUSR1))
[E/utest] [  FAILED  ] [ result   ] testcase (testcases.kernel.signal_tc)

在 rt_signal_wait_thread 中，通过 (void)sigaddset(&selectset, SIGUSR1)将信号 SIGUSR1 添加到 selectset 中。但在使用 musl-libc 时，sigaddset接口将*selectset 被设置为 (*selectset) | (1 << (signo - 1))。这导致在 rt_signal_wait 函数中的 if (sig_mask(signo) & *set)（第403行）判断条件不满足。

你的解决方案是什么 (what is your solution)

在使用musl-libc时，#define sig_mask(sig_no) (1u << (sig_no - 1))，与sigaddset接口的实现保持一致；

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

• BSP: bsp/qemu-virt64-riscv

• .config: RT_USING_MUSLLIBC =y

• action:

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• 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
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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