libaom encoder not outputting packets

To reproduce, use raw input:

./vlc -vv  -I "dummy" ~/Videos/akiyo_qcif.y4m --stop-time 2 --rawvid-chroma I420 --rawvid-fps 25 --sout="#transcode{vcodec=av01,venc=aom}:std{access=file,mux=avformat,dst='test-video.ivf'}" vlc://qui

It seems to be a pts issue, as the attached patch works around the problem.