qt_imageFromVideoFrame" no longer exists in Qt5.15.0

[mwbrown42]

As described by "mw2785" in https://stackoverflow.com/questions/27829830/convert-qvideoframe-to-qimage:

_For anyone ending up here after finding that the qt private function "qt_imageFromVideoFrame" no longer exists in Qt5.15.0, you can now use the newly implemented method QImage QVideoFrame::image().

QImage img = frame.image();

I've tested this on Ubuntu and it works._

I tested this fix on Qt on Windows and it works.

I also want to add that you, Stephen Quan, are a steely-eyed missile man! Thanks for all the work you put into this.