Derive QPpsObjectPrivate from QObjectPrivate

Fixes 5d4089299a commit,
which was causing a build break if qnx pps is enabled.

Change-Id: I8c29f48bde0187a9db02d6325e8a9a0fae760bcb
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@qt.io>

src/corelib/kernel/qppsobjectprivate_p.h

@@ -57,13 +57,15 @@
 #include <QDebug>
 
 #include <sys/pps.h>
+#include <private/qobject_p.h>
 
 QT_BEGIN_NAMESPACE
 
 class QSocketNotifier;
 
-class QPpsObjectPrivate
+class QPpsObjectPrivate : public QObjectPrivate
 {
+    Q_DECLARE_PUBLIC(QPpsObject)
 public:
     explicit QPpsObjectPrivate(const QString &path);