[clang] [CIR] Implement__builtin_va_arg (PR #153834)

[Henrich Lauko via cfe-commits]

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@@ -384,6 +384,19 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
     return Visit(e->getReplacement());
   }
 
+  mlir::Value VisitVAArgExpr(VAArgExpr *ve) {
+    QualType Ty = ve->getType();
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xlauko wrote:

```suggestion
    QualType ty = ve->getType();
```

https://github.com/llvm/llvm-project/pull/153834