pythongh-106320: Remove private _PyModule API (python#107070)

Move private _PyModule API to the internal C API
(pycore_moduleobject.h):

* _PyModule_Clear()
* _PyModule_ClearDict()
* _PyModuleSpec_IsInitializing()
* _PyModule_IsExtension()

No longer export these functions.

Include/internal/pycore_moduleobject.h

@@ -8,6 +8,12 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE define"
 #endif
 
+extern void _PyModule_Clear(PyObject *);
+extern void _PyModule_ClearDict(PyObject *);
+extern int _PyModuleSpec_IsInitializing(PyObject *);
+
+extern int _PyModule_IsExtension(PyObject *obj);
+
 typedef struct {
     PyObject_HEAD
     PyObject *md_dict;

Include/moduleobject.h

@@ -27,11 +27,6 @@ PyAPI_FUNC(PyObject *) PyModule_GetNameObject(PyObject *);
 PyAPI_FUNC(const char *) PyModule_GetName(PyObject *);
 Py_DEPRECATED(3.2) PyAPI_FUNC(const char *) PyModule_GetFilename(PyObject *);
 PyAPI_FUNC(PyObject *) PyModule_GetFilenameObject(PyObject *);
-#ifndef Py_LIMITED_API
-PyAPI_FUNC(void) _PyModule_Clear(PyObject *);
-PyAPI_FUNC(void) _PyModule_ClearDict(PyObject *);
-PyAPI_FUNC(int) _PyModuleSpec_IsInitializing(PyObject *);
-#endif
 PyAPI_FUNC(PyModuleDef*) PyModule_GetDef(PyObject*);
 PyAPI_FUNC(void*) PyModule_GetState(PyObject*);
 
@@ -103,12 +98,6 @@ struct PyModuleDef {
   freefunc m_free;
 };
 
-
-// Internal C API
-#ifdef Py_BUILD_CORE
-extern int _PyModule_IsExtension(PyObject *obj);
-#endif
-
 #ifdef __cplusplus
 }
 #endif