* Moves the `GET_ITER` instruction into the generator function preamble.
This means the the iterable is converted into an iterator during generator
creation, as documented, but keeps it in the same code object allowing
optimization.
Move some `#include <stdbool.h>` after `#include "Python.h"` when `pyconfig.h` is not
included first and when we are in a platform-agnostic context. This is to avoid having
features defined by `stdbool.h` before those decided by `Python.h`.
