[clang] [CIR] Use alloca address space for CallConvLowering temporaries (PR #229792)

[Konstantinos Parasyris via cfe-commits]

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koparasy wrote:

These are still created in the default AS. Should we maybe handle them in this PR? I am not sure whether this is reachable now. 

https://github.com/llvm/llvm-project/pull/229792