Use the V4L2 buffer orphaning feature, exposed through V4L2VideoDevice::exportBuffers(), to decouple buffer import and export. The PipelineHandler::importFrameBuffers() function is now called for all streams regardless of whether exportFrameBuffers() has been called or not. This simplifies the Camera implementation slightly, and opens the door to additional simplifications. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>