Hide log out button when auth is not enabled (#9158)

This was an oversight in #8757: the new "Log out" button is always shown
in the "Actions" menu, even when authentication is not enabled.

gui/default/syncthing/core/syncthingController.js

@@ -565,6 +565,15 @@ angular.module('syncthing.core')
             }).error($scope.emitHTTPError);
         }
 
+        $scope.isAuthEnabled = function () {
+            // This function should match IsAuthEnabled() in guiconfiguration.go
+            var guiCfg = $scope.config && $scope.config.gui;
+            if (guiCfg) {
+                return guiCfg.authMode === 'ldap' || (guiCfg.user && guiCfg.password);
+            }
+            return false;
+        };
+
         function refreshNoAuthWarning() {
             if (!$scope.system || !$scope.config || !$scope.config.gui) {
                 // We need all to be able to determine the state.
@@ -579,8 +588,7 @@ angular.module('syncthing.core')
             $scope.openNoAuth = addr.substr(0, 4) !== "127."
                 && addr.substr(0, 6) !== "[::1]:"
                 && addr.substr(0, 1) !== "/"
-                && (!guiCfg.user || !guiCfg.password)
-                && guiCfg.authMode !== 'ldap'
+                && !$scope.isAuthEnabled()
                 && !guiCfg.insecureAdminAccess;
 
             if ((guiCfg.user && guiCfg.password) || guiCfg.authMode === 'ldap') {