Enable optimized builds for steam deck.

nix/steam_deck/configuration/roles/global_options/default.nix

@@ -0,0 +1,19 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  imports = [ ];
+
+  options.me = {
+    optimizations.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = "Whether we want to enable CPU optimizations (will trigger a rebuild from source).";
+    };
+  };
+}