Add v4l2codecs plugin to support Linux V4L2 Stateless CODECs drivers
This patchset add support for V4L2 Stateless CODECs drivers. These CODECs are a bit similar to VAAPI as they only implement the core decoding function. This plugin shares the parsing and the state management used for DXVA CODEC, a very similar interface for Microsoft Windows.
This has been tested on i.MX8M (Hantro), Rockchip RK3288 (Hantro) and RK3399 (RKVDEC). It supports only H264 for now. Extra work is needed to support Allwinner platforms, this will be added in future submissions.