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

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

For very old clang code, we were less rigorous about test checks; these days we'd very rarely approve -emit-llvm-only tests.  Especially since we have update_cc_test_checks.py.

It probably makes sense to change the test to an update_cc_test_checks.py test, just so nobody changes complex codegen by accident.

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