[clang] [clang] Report erroneous floating point results in _Complex math (PR #90588)

[Joshua Cranmer via cfe-commits]

https://github.com/jcranmer-intel commented:

After banging my head on the desk trying to figure out why the tests were giving such strange results, I realized the issue...

Could you please use `__builtin_complex` in the test to construct the complex infinities instead of `__builtin_infinity() * 1.0j`?

https://github.com/llvm/llvm-project/pull/90588