AVFoundation: implement QCameraInfoControl.

Change-Id: I05f3daa5c4acb90e046e26d6d577ae40dfed0e30
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
AVFoundation: Cleanup AVCaptureSession with proper reference counting

The reference counting was not being done for AVCaptureSession so it was
being destroyed before we got a chance to properly clean it up (which
lead to crashes).  We also make sure to remove any observers from
AVCaptureSession now before destroying it.

Task-number: QTBUG-37109
Task-number: QTBUG-29955
Change-Id: Ia9b49ad1eab01b4f7424e2a1c699d903cd9bf902
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>
enable imx6 specific QSGVideoNode based on a config test

This way it also works custom mkspecs

Change-Id: I7414aac775b797da3487e9625c7212486118b532
Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
videonode: imx6: cleanup pixel formats

All formats are now tested.

Also, don't use the alpha channel. This is not quite correct for formats
with alpha channel but for video probably a good idea.

Change-Id: I4a2404d7c96023bb1e3fca41e1f224d23347f290
Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
videonode: imx6: clear texture cache when the format changes

The old textures won't match anyways. So there is no need to keep them.

Change-Id: Id3482333d10cf022d04076ec0f5c7df475c522ae
Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
Reviewed-by: Andy Nichols <andy.nichols@digia.com>