[clang] [clang] Improve diagnostics for invalid named-universal-characters (PR #206326)

[Timm Baeder via cfe-commits]

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@@ -1085,6 +1085,26 @@ void clang::EscapeStringForDiagnostic(StringRef Str,
   }
 }
 
+/// DisplayCodePointForDiagnostic - Display CodePoint in U+NNNN notation,
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tbaederr wrote:

```suggestion
/// Display CodePoint in U+NNNN notation,
```

https://github.com/llvm/llvm-project/pull/206326