[clang] [OpenACC][CIR] Implement atomic-write lowering (PR #164627)

[Robert Imschweiler via cfe-commits]

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@@ -821,6 +821,7 @@ class OpenACCAtomicConstruct final
   struct StmtInfo {
     const Expr *V;
     const Expr *X;
+    const Expr *Expr;
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ro-i wrote:

I think this leads to build errors due to clash with declaration of `clang::Expr` in `clang/include/clang/AST/Expr.h`

https://github.com/llvm/llvm-project/pull/164627