Add test to test the different modes and situations the V4L2BufferCache
can be put in. The tests verify that a FrameBuffer used with the cache
results in a V4L2 video device index, and that the cache implementation
is capable of keeping buffers in a hot state.
Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
