C API: Add `Py_GetBuildInType` and `Py_GetBuildInTypeBorrowed`

[vstinner (Victor Stinner)]

@vstinner

Only RustPython seems to have an issue with accessing a built-in type (&PyBool_Type) in #define PyBool_Check(x) Py_IS_TYPE((x), &PyBool_Type) macro. You can modify the C API implementation in RustPython, but not modify CPython.

@bschoenmaeckers: What do you think? Can you fix the issue in RustPython?

Oops. I meant: I don’t get the motivation to modify CPython.