[clang-tools-extra] [clang-tidy] Fix false positive in readability-redundant-preprocessor for builtin checks (PR #181734)

[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/readability/RedundantPreprocessorCheck.cpp |
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/readability/RedundantPreprocessorCheck.cpp:43:5: warning: variable 'Condition' of type 'StringRef' can be declared 'const' [misc-const-correctness]
   43 |     StringRef Condition = getConditionText(Loc);
      |     ^
      |               const 
clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp:81:5: warning: variable 'SpellingLoc' of type 'SourceLocation' can be declared 'const' [misc-const-correctness]
   81 |     SourceLocation SpellingLoc = SM.getSpellingLoc(Loc);
      |     ^
      |                    const 
clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp:83:5: warning: variable 'AfterIf' of type 'SourceLocation' can be declared 'const' [misc-const-correctness]
   83 |     SourceLocation AfterIf =
      |     ^
      |                    const 
clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp:90:5: warning: variable 'Buffer' of type 'StringRef' can be declared 'const' [misc-const-correctness]
   90 |     StringRef Buffer = SM.getBufferData(FID, &Invalid);
      |     ^
      |               const 
clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp:97:7: warning: variable 'C' of type 'char' can be declared 'const' [misc-const-correctness]
   97 |       char C = Buffer[End];
      |       ^
      |            const
```

</details>


https://github.com/llvm/llvm-project/pull/181734