QPainterPath: replace a use of QList<QRectF> with a QVector

QList<QRectF> is horribly inefficent, and this is just implementation,
so we're free to change it.

Change-Id: I7b28a2093efb5826b55c172f48a81cb9c2472e5a
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/gui/painting/qpainterpath.cpp

@@ -1644,7 +1644,8 @@ QList<QPolygonF> QPainterPath::toFillPolygons(const QTransform &matrix) const
     if (count == 0)
         return polys;
 
-    QList<QRectF> bounds;
+    QVector<QRectF> bounds;
+    bounds.reserve(count);
     for (int i=0; i<count; ++i)
         bounds += subpaths.at(i).boundingRect();