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

[Timm Baeder via cfe-commits]

================
@@ -2774,7 +2774,8 @@ static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
     if (Info.checkingForUndefinedBehavior())
       Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
                                        diag::warn_integer_constant_overflow)
-          << toString(Result, 10) << E->getType() << E->getSourceRange();
+          << toString(Result, 10, Result.isSigned(), false, true, true)
----------------
tbaederr wrote:

```suggestion
          << toString(Result, 10, Result.isSigned(), /*formatAsCLiteral=*/false, /*upperCase=*/true, /*insertSeparators=*/true)
```

same with the other callsite.

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