[clang] Return larger CXX records in memory (#120670)
We incorrectly return CXX records in AVX registers when they should be
returned in memory. This is violation of x86-64 psABI.
Detailed discussion is here:
https://groups.google.com/g/x86-64-abi/c/BjOOyihHuqg/m/KurXdUcWAgAJ
