[clang] [llvm] [clang] Use separator for large numeric values in overflow diagnostic (PR #80939)

[Timm Baeder via cfe-commits]

================
@@ -2187,6 +2188,12 @@ void APInt::toString(SmallVectorImpl<char> &Str, unsigned Radix, bool Signed,
     }
   }
 
+  // Number of digits in a group between separators
----------------
tbaederr wrote:

```suggestion
  // Number of digits in a group between separators.
```

https://github.com/llvm/llvm-project/pull/80939