[clang-tools-extra] [clang-tidy] add modernize-use-constexpr check (PR #146553)

[via cfe-commits]

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+.. title:: clang-tidy - modernize-use-constexpr
+
+modernize-use-constexpr
+=======================
+
+Finds functions and variables that can be declared 'constexpr'.
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EugeneZelenko wrote:

```suggestion
Finds functions and variables that can be declared '`constexpr'`.
```

https://github.com/llvm/llvm-project/pull/146553