[clang-tools-extra] added option `llvm-header-guard.HeaderDirs` (PR #176940)

[via cfe-commits]

github-actions[bot] wrote:

<!--LLVM CODE LINT COMMENT: clang-tidy-->


:warning: C/C++ code linter, clang-tidy found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

```bash

git diff -U0 origin/main...HEAD -- clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.h |
python3 clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py   -path build -p1 -quiet
```

</details>

<details>
<summary>
View the output from clang-tidy here.
</summary>

```

clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp:34:8: warning: variable 'HeaderDir' of type 'StringRef' can be declared 'const' [misc-const-correctness]
   34 |   for (StringRef HeaderDir : HeaderDirs) {
      |        ^
      |                  const 
clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp:35:5: warning: variable 'PosHeaderDir' of type 'size_t' (aka 'unsigned long') can be declared 'const' [misc-const-correctness]
   35 |     size_t PosHeaderDir = Guard.rfind(HeaderDir.str() + "/");
      |     ^
      |            const
```

</details>


https://github.com/llvm/llvm-project/pull/176940