nixos/fontconfig-ultimate: Restore presets

The `preset` option was accidentally removed.

nixos/modules/config/fonts/fontconfig-ultimate.nix

@@ -63,6 +63,15 @@ in
               <literal>none</literal> disables the substitutions.
             '';
           };
+
+          preset = mkOption {
+            type = types.enum ["ultimate1" "ultimate2" "ultimate3" "ultimate4" "ultimate5" "osx" "windowsxp"];
+            default = "ultimate3";
+            description = ''
+              FreeType rendering settings preset. Any of the presets may be
+              customized by setting environment variables.
+            '';
+          };
         };
       };
     };
@@ -72,6 +81,7 @@ in
   config = mkIf (config.fonts.fontconfig.enable && cfg.enable) {
 
     fonts.fontconfig.confPackages = [ confPkg ];
+    environment.variables."INFINALITY_FT" = cfg.preset;
 
   };