[llvm] [DI] Have createClassType create a class type. (PR #102624)

[David Blaikie via llvm-commits]

dwblaikie wrote:

this'll need test coverage - but also, what does Clang do? (does it use a different API? Perhaps this API you're updating is unused/dead and that would help explain why it's incorrect - in which case removing it might be the better option?)

https://github.com/llvm/llvm-project/pull/102624