[clang] [CIR] Recognize constant aggregate initialization of auto vars (PR #166850)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

> I've reverted this in [ec21e58](https://github.com/llvm/llvm-project/commit/ec21e58a30b2855e1e0140d417031281f2675a54) given it doesn't seem like a forward fix is eminent.

Yeah, my apologies to everyone. I didn't realize my change was causing the failure since it didn't modify any code that is even built by the buildbots. It seems I let a change to an unrelated test sneak into my commit.

https://github.com/llvm/llvm-project/pull/166850