[clang] [libclang/python] Do not rely on `ctypes`' `errcheck` (PR #105490)

[Jannick Kremer via cfe-commits]

https://github.com/DeinAlptraum commented:

@Endilll this removes the `errcheck` magic conversion stuff that we discussed the other day

https://github.com/llvm/llvm-project/pull/105490