Encode* does not set picture numbers correctly

[GalenReich]

Picture numbers must have consecutive, ascending integer values, wrapping at (2**32)-1 back to 0.

Using EncodeHQ-ConstQ to encode the real_pictures file with

EncodeHQ-ConstQ \
    -x 1280 -y 720 -f 4:2:2 -z 10 -r 6 \
    -k LeGall -d 3 -a 2 -u 1 -v -q 0 -S 2 \
   ./real_pictures.16p2 ./encoded_real_pictures.vc2

gives a non-conformat bitstream with sequential pictures having a picture number of zero. It also gives a nonconformant stream when the interlaced flag (-i) is set

Encode_CBR produces nonconformant bitstream with the same error if the interlaced flag is set (but not otherwise).