pythongh-125038: PyIter_Checks are added for some FOR_ITER bytecodes

SIGSEGV on generators in case of gi_frame.f_locals is fixed.
This applies to _FOR_ITER bytecode.
Similar checks are added to _FOR_ITER_TIER_TWO and INSTRUMENTED_FOR_ITER bytecode implementations.

Python/bytecodes.c

@@ -2804,7 +2804,10 @@ dummy_func(
         replaced op(_FOR_ITER, (iter -- iter, next)) {
             /* before: [iter]; after: [iter, iter()] *or* [] (and jump over END_FOR.) */
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
-            PyObject *next_o = (*Py_TYPE(iter_o)->tp_iternext)(iter_o);
+            PyObject *next_o = NULL;
+            if (PyIter_Check(iter_o)) {
+                next_o = (*Py_TYPE(iter_o)->tp_iternext)(iter_o);
+            }
             if (next_o == NULL) {
                 if (_PyErr_Occurred(tstate)) {
                     int matches = _PyErr_ExceptionMatches(tstate, PyExc_StopIteration);
@@ -2830,7 +2833,10 @@ dummy_func(
         op(_FOR_ITER_TIER_TWO, (iter -- iter, next)) {
             /* before: [iter]; after: [iter, iter()] *or* [] (and jump over END_FOR.) */
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
-            PyObject *next_o = (*Py_TYPE(iter_o)->tp_iternext)(iter_o);
+            PyObject *next_o = NULL;
+            if (PyIter_Check(iter_o)) {
+                next_o = (*Py_TYPE(iter_o)->tp_iternext)(iter_o);
+            }
             if (next_o == NULL) {
                 if (_PyErr_Occurred(tstate)) {
                     int matches = _PyErr_ExceptionMatches(tstate, PyExc_StopIteration);
@@ -2854,7 +2860,10 @@ dummy_func(
             _Py_CODEUNIT *target;
             _PyStackRef iter_stackref = TOP();
             PyObject *iter = PyStackRef_AsPyObjectBorrow(iter_stackref);
-            PyObject *next = (*Py_TYPE(iter)->tp_iternext)(iter);
+            PyObject *next = NULL;
+            if (PyIter_Check(iter)) {
+                next = (*Py_TYPE(iter)->tp_iternext)(iter);
+            }
             if (next != NULL) {
                 PUSH(PyStackRef_FromPyObjectSteal(next));
                 target = next_instr;