Make sure QQuickBorderImage sets its pixmapChanged dirtyflag
Make sure QQuickBorderImage sets its pixmapChanged dirtyflag

Task-number: QTBUG-34298

Change-Id: Ie66f0bdd705335491496f5d583193b32cb7749f3
Reviewed-by: Alan Alpert <da25f2afbbb946022229108d81aeba0c6b35c5c3@blackberry.com>

qmlc/qtdeclarative,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d