[clang] [Clang] Warn on backslash-newline-EOF (PR #97585)

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https://github.com/Sirraide approved this pull request.

Thanks, I personally at least find it much easier to tell now at a glance that this makes sense. I’d wait a bit before merging this to see if someone more familiar with either C or the lexer has any more comments on this,.

https://github.com/llvm/llvm-project/pull/97585