[clang-tools-extra] [clang-tidy] Add detection of decltype(nullptr) => std::nullptr_t to modernize-use-nullptr (PR #224591)

[Yanzuo Liu via cfe-commits]

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@@ -51,6 +61,16 @@ Options
    ``NULL``. By default this check will only replace the ``NULL`` macro and will
    skip any similar user-defined macros.
 
+.. option:: useNullptrt
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zwuis wrote:

Should start with a upper-case letter.

https://github.com/llvm/llvm-project/pull/224591