gh-90623: signal.raise_signal() calls PyErr_CheckSignals() (#91756)

signal.raise_signal() and os.kill() now call PyErr_CheckSignals() to
check immediately for pending signals.

Modules/signalmodule.c

@@ -481,6 +481,13 @@ signal_raise_signal_impl(PyObject *module, int signalnum)
     if (err) {
         return PyErr_SetFromErrno(PyExc_OSError);
     }
+
+    // If the current thread can handle signals, handle immediately
+    // the raised signal.
+    if (PyErr_CheckSignals()) {
+        return NULL;
+    }
+
     Py_RETURN_NONE;
 }