grsecurity module: fix grsec-lock unit ordering

Requirement without ordering implies parallel execution; it is crucial
that sysctl tunables are finalized before the lock is engaged, however.

(cherry picked from commit 60a27781d6d358e0c5cd144c7c90642761c1a31f)

nixos/modules/security/grsecurity.nix

···
 
     systemd.services.grsec-lock = mkIf cfg.config.sysctl {
       description     = "grsecurity sysctl-lock Service";
-      requires        = [ "systemd-sysctl.service" ];
+      wants           = [ "systemd-sysctl.service" ];
+      after           = [ "systemd-sysctl.service" ];
       wantedBy        = [ "multi-user.target" ];
       serviceConfig.Type = "oneshot";
       serviceConfig.RemainAfterExit = "yes";