[clang] [CIR] Upstream emitAndUpdateRetAlloca (PR #129933)

[Erich Keane via cfe-commits]

================
@@ -49,6 +49,8 @@ class CIRGenFunction : public CIRGenTypeCache {
 
 public:
   clang::QualType fnRetTy;
----------------
erichkeane wrote:

Actually I question the need for `fnRetTy` too, particularly since `fnRetQualTy` and `fnRetTy` are not being set together...

https://github.com/llvm/llvm-project/pull/129933