Cleanup QtWidgets animation examples

Cleanup the QtWidgets animation examples:
 - use nullptr
 - use normalized includes, remove unused includes
 - fix style
 - fix crash of sub-attaq when the game ended (error during range-based
   for loop porting)
 - don't use keyword 'final' for a variable name

Change-Id: Id23be8ff8b1b310da005d13c052fe547f6a0d63a
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 4 insertions, 13 deletions

diff --git a/examples/widgets/animation/sub-attaq/animationmanager.cpp b/examples/widgets/animation/sub-attaq/animationmanager.cpp
index a611641613..261cbd1e1c 100644
--- a/examples/widgets/animation/sub-attaq/animationmanager.cpp
+++ b/examples/widgets/animation/sub-attaq/animationmanager.cpp
@@ -51,22 +51,13 @@
 //Own
 #include "animationmanager.h"
 
-//Qt
-#include <QtCore/QAbstractAnimation>
-#include <QtCore/QDebug>
-
-// the universe's only animation manager
-AnimationManager *AnimationManager::instance = nullptr;
-
-AnimationManager::AnimationManager()
-{
-}
+#include <QAbstractAnimation>
 
 AnimationManager *AnimationManager::self()
 {
-    if (!instance)
-        instance = new AnimationManager;
-    return instance;
+    // the universe's only animation manager
+    static AnimationManager s_instance;
+    return &s_instance;
 }
 
 void AnimationManager::registerAnimation(QAbstractAnimation *anim)