[clang] [Clang][CodeGen] Make UnqualPtrTy match llvm::PointerType::getUnqual (PR #163207)

[Juan Manuel Martinez Caamaño via cfe-commits]

jmmartinez wrote:

Just to propose another approach to the problem, it really looks like the issue is mainly a naming issue more than anything.

We could rename `UnqualPtrTy` to `DefaultPtrTy` or `GenericPtrTy` which would be closer to its current meaning. If some part of clang really needs the address-space 0 pointer, it can still use `PointerType::getUnqual`.

https://github.com/llvm/llvm-project/pull/163207