ZyklonB, kike: Use pledge(2) in OpenBSD

degesch has something like "stdio wpath cpath inet tty proc exec"
but given that it's user-extensible and very annoying for users to
have it crash, I'm leaving it unrestricted for now.

kike.c

@@ -4076,6 +4076,12 @@ main (int argc, char *argv[])
 	else if (!irc_lock_pid_file (&ctx, &e))
 		exit_fatal ("%s", e->message);
 
+#if OpenBSD >= 201605
+	// This won't be as simple once we decide to implement REHASH
+	if (pledge ("stdio inet dns", NULL))
+		exit_fatal ("%s: %s", "pledge", strerror (errno));
+#endif
+
 	ctx.polling = true;
 	while (ctx.polling)
 		poller_run (&ctx.poller);