[clang-tools-extra] [llvm] New check `misc-header-guard` (PR #177315)

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EugeneZelenko wrote:

> I have added option `AllowPragmaOnce` so that the check does not warn if `#pragma once` is used. I hope it is
> 
> > Replace #pragma once with guard.
> 
> Would it be acceptable to handle this in a follow-up PR? I’m unsure how to get the `Loc` correctly, since most of the work is done in the base class `utils::HeaderGuardCheck`.

Sure, this may be implemented separately.

https://github.com/llvm/llvm-project/pull/177315