bpo-43356: Allow passing a signal number to interrupt_main() (GH-24755)

Also introduce a new C API ``PyErr_SetInterruptEx(int signum)``.

Include/pyerrors.h

@@ -224,6 +224,9 @@ PyAPI_FUNC(void) PyErr_WriteUnraisable(PyObject *);
 /* In signalmodule.c */
 PyAPI_FUNC(int) PyErr_CheckSignals(void);
 PyAPI_FUNC(void) PyErr_SetInterrupt(void);
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030A0000
+PyAPI_FUNC(int) PyErr_SetInterruptEx(int signum);
+#endif
 
 /* Support for adding program text to SyntaxErrors */
 PyAPI_FUNC(void) PyErr_SyntaxLocation(