When a NvVideoEncoder is created with the
O_NONBLOCK flag, calls to v4l2_ioctl(…) still seem to block, most critically
v4l2_ioctl(fd, VIDIOC_DQBUF, &v4l2_buf) blocks.
Is there any way/plan to fix this? (I could also get around this problem if there is a way to poll to see if there is a buffer available to dq).