All these in multiprocessing.h are lacking suitable py/_py/Py/_Py/PY/_PY
prefixes:

PyObject *mp_SetError(PyObject *Type, int num);
extern PyObject *pickle_dumps;
extern PyObject *pickle_loads;
extern PyObject *pickle_protocol;
extern PyObject *BufferTooShort;
extern PyTypeObject SemLockType;
extern PyTypeObject ConnectionType;
extern PyTypeObject PipeConnectionType;
extern HANDLE sigint_event;

Additionally, win32_functions.c exposes Win32Type and
create_win32_namespace.

semaphore.c has sem_timedwait_save.

multiprocessing.c has ProcessError.