Re: Don't use the deprecated and insecure PQcancel in our frontend tools anymore

Hello

+void
+setup_cancel_handler(void (*signal_callback) (void),
+					 void (*thread_callback) (void))
+{
+...
+	create_cancel_thread();
+	pqsignal(SIGINT, CancelSignalHandler);
+#endif
+}

Maybe this should have a doc comment explaining that this function
should only be called once (or alternatively, create_cancel_thread
should have a guard against repeated callers)?