Charts opengl accelerated series do no longer work on c++ side

Seems that QtBase commit 5c7f000cd4c9e3769e8cd4085cf0beee104f9886 reduced QOpenGLWidget paint events, and charts was relying on some of those events that no longer come to update opengl accelerated series. Charts needs to explicitly update its QOpenGLWidget when in needs to be redrawn.