Add Q_ENUM for QNetworkAccessManager::NetworkAccessibility.

This is needed for generic property access to work correctly.

Change-Id: I88cd40238a8caf8df6c71b22e2fa0c4d5655a88a
Reviewed-by: Richard J. Moore <rich@kde.org>

src/network/access/qnetworkaccessmanager.h

@@ -94,6 +94,7 @@ public:
         NotAccessible = 0,
         Accessible = 1
     };
+    Q_ENUM(NetworkAccessibility)
 #endif
 
     explicit QNetworkAccessManager(QObject *parent = Q_NULLPTR);