Originated from #1858 and #1914.

Two commits that cause desync at speed 0,1,2 are:
3c79e02 and
db0da3c
those might cause the desync from different origins, but given that temporary fix of disabling segmentation (as in #1914) indicates that encoding of segment id might cause issue.

A set of test runs to see desync that I used can be:
./target/release/rav1e nyan.y4m -o test.ivf -r test_rec.y4m --quantizer 50 --speed=0 --limit=30
./target/release/rav1e nyan.y4m -o test.ivf -r test_rec.y4m --quantizer 50 --speed=1 --limit=30
./target/release/rav1e nyan.y4m -o test.ivf -r test_rec.y4m --quantizer 50 --speed=2 --limit=30

Note that the desync happens regardless of --tune.