[clang] [Clang] Fix Codegen UO real/imag crash on scalar with type promotion (PR #160609)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

> I realized that in Codegen complex test, it checks for `clang_cc1 -emit-llvm-only` (Not all of them) without checking the IR itself. Maybe we can share our tests from ClangIR because it already checks the IR, and it's covering more features for ComplexType than the current tests in classical codegen
> 
> CC. @andykaylor @bcardosolopes

It is a bit odd that there are no checks for the IR produced. There's more coverage in other tests, like complex-math.c. I'm not clear what the intent of this test is, but for your change that is basically just correcting a crash, this seems sufficient.

https://github.com/llvm/llvm-project/pull/160609