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

[Oliver Hunt via cfe-commits]

https://github.com/ojhunt approved this pull request.

ObjC blocks: the gift that keeps on giving :D

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?

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