QSequentialAnimationGroupPrivate: replace an inefficient QList with QVector

ints are only half the size of void* on 64-bit, so
QVector<int> uses only 50% of per-element memory,
compared to a QList.

Change-Id: I18db97d2ec0e46ec4301e8939ac21dff558172b2
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/corelib/animation/qsequentialanimationgroup_p.h

@@ -86,7 +86,7 @@ public:
 
     // this is the actual duration of uncontrolled animations
     // it helps seeking and even going forward
-    QList<int> actualDuration;
+    QVector<int> actualDuration;
 
     void restart();
     int lastLoop;