[clang] [llvm] [LLVMABI] Handle Atomic types in the LLVM ABI library (PR #221367)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

> Please make sure we have an open issue for the ABI incompatibility. But I agree we shouldn't try to modify it in this patch.

https://github.com/llvm/llvm-project/issues/222104

https://github.com/llvm/llvm-project/pull/221367