gh-106320: Remove private _Py_ForgetReference() (#108664)

Move the private _Py_ForgetReference() function to the internal C API
(pycore_object.h).

Author: vstinner

Include/cpython/object.h

@@ -5,11 +5,6 @@
 PyAPI_FUNC(void) _Py_NewReference(PyObject *op);
 PyAPI_FUNC(void) _Py_NewReferenceNoTotal(PyObject *op);
 
-#ifdef Py_TRACE_REFS
-/* Py_TRACE_REFS is such major surgery that we call external routines. */
-PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
-#endif
-
 #ifdef Py_REF_DEBUG
 /* These are useful as debugging aids when chasing down refleaks. */
 PyAPI_FUNC(Py_ssize_t) _Py_GetGlobalRefTotal(void);

Include/internal/pycore_object.h

@@ -31,6 +31,11 @@ extern void _PyDebugAllocatorStats(FILE *out, const char *block_name,
 
 extern void _PyObject_DebugTypeStats(FILE *out);
 
+#ifdef Py_TRACE_REFS
+/* Py_TRACE_REFS is such major surgery that we call external routines. */
+PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
+#endif
+
 // Export for shared _testinternalcapi extension
 PyAPI_FUNC(int) _PyObject_IsFreed(PyObject *);