expose _PyGC_VisitFrameStack and _PyGC_VisitStackRef

Author: kumaraditya303

Include/internal/pycore_gc.h

@@ -335,8 +335,8 @@ extern void _Py_RunGC(PyThreadState *tstate);
 union _PyStackRef;
 
 // GC visit callback for tracked interpreter frames
-extern int _PyGC_VisitFrameStack(_PyInterpreterFrame *frame, visitproc visit, void *arg);
-extern int _PyGC_VisitStackRef(union _PyStackRef *ref, visitproc visit, void *arg);
+PyAPI_FUNC(int) _PyGC_VisitFrameStack(_PyInterpreterFrame *frame, visitproc visit, void *arg);
+PyAPI_FUNC(int) _PyGC_VisitStackRef(union _PyStackRef *ref, visitproc visit, void *arg);
 
 #ifdef Py_GIL_DISABLED
 extern void _PyGC_VisitObjectsWorldStopped(PyInterpreterState *interp,