openh264enc: Remove broken byte-stream to avc conversion and just output byte-stream...

openh264enc: Remove broken byte-stream to avc conversion and just output byte-stream as generated by the encoder

The byte-stream to avc conversion did not consider NAL sizes bigger than 2^16,
multiple layers, multiple NALs per layer, and various other things. This
caused corrupted streams in higher bitrates and other circumstances.

Let's just forward byte-stream as generated by the encoder and let h264parse
handle conversion to avc if needed. That way we only have to keep around one
version of the conversion and don't have to fix it in multiple places.