"system-auth" doesn't exist on non-Linux.

pam_unix(8) requires root priveleges to access master.passwd(5),
so try authenticating via setuid helper first.

--- pam.d/waylock.orig	2023-01-08 18:59:32 UTC
+++ pam.d/waylock
@@ -1 +1 @@
-auth include system-auth
+auth include unix-selfauth