Fix memory leak of QFontEngineData

Move QFont::cleanup(); and cleanupThreadData(); to the end of destructor
of QGuiApplicationPrivate class. This is because they will trigger the
QFontCache::~QFontCache() function being called and at that time the
platform_theme object still hold some fonts object, This will cause the
QFontEngineData object hold by those fonts can never been deleted.

Change-Id: I4d3f21c5e2683706f68395ba3ad24203081e1d1d
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>

src/gui/kernel/qguiapplication.cpp

@@ -875,16 +875,12 @@ QGuiApplicationPrivate::~QGuiApplicationPrivate()
 
     clearFontUnlocked();
 
-    QFont::cleanup();
-
 #ifndef QT_NO_CURSOR
     QCursorData::cleanup();
 #endif
 
     layout_direction = Qt::LeftToRight;
 
-    cleanupThreadData();
-
     delete styleHints;
     delete inputMethod;
 
@@ -896,6 +892,10 @@ QGuiApplicationPrivate::~QGuiApplicationPrivate()
     delete platform_integration;
     platform_integration = 0;
     delete m_gammaTables.load();
+
+    QFont::cleanup();
+
+    cleanupThreadData();
 }
 
 #if 0