[clang] [clang][bytecode] Fix `Pointer::getType()` for ObjC blocks (PR #232186)

[Timm Baeder via cfe-commits]

tbaederr wrote:

> I _assume_ (hope?) that blocks with associated captures are not represented as `FunctionDecl`s, is it worth adding a new test or is that already covered elsewhere?

I'm pretty sure they aren't, but I couldn't tell you if that's tested anywhere.

https://github.com/llvm/llvm-project/pull/232186