Check for trailing marker/zero bits for tile data.

Fixes #385 (closed).

$ ninja && for tc in '--threads=1' '--threads 2 --framedelay=1' '--threads=4 --framedelay=2'; do for s in 0 1; do tools/dav1d --demuxer=ivf -i ~/Downloads/fuzzy.ivf --muxer=null --strict $s $tc; echo '---'; done; done 
[8/8] Linking target examples/dav1dplay
dav1d 1.3.0-84-gaa078d49 - by VideoLAN
Decoded 3/2 frames (150.0%) - 1385.04/1.00 fps (1385.04x)Error parsing OBU data
Error decoding frame: Invalid argument

---
dav1d 1.3.0-84-gaa078d49 - by VideoLAN
Error decoding frame: Invalid argument
Error parsing frame header
Error parsing OBU data
Error decoding frame: Invalid argument
No data decoded
---
dav1d 1.3.0-84-gaa078d49 - by VideoLAN
Decoded 3/2 frames (150.0%) - 1339.29/1.00 fps (1339.29x)Error parsing OBU data
Error decoding frame: Invalid argument

---
dav1d 1.3.0-84-gaa078d49 - by VideoLAN
Error decoding frame: Invalid argument
Error parsing frame header
Error parsing OBU data
Error decoding frame: Invalid argument
No data decoded
---
dav1d 1.3.0-84-gaa078d49 - by VideoLAN
Decoded 1/2 frames (50.0%) - 783.09/1.00 fps (783.09x)Error parsing OBU data
Error decoding frame: Invalid argument
Decoded 3/2 frames (150.0%) - 1746.22/1.00 fps (1746.22x)
---
dav1d 1.3.0-84-gaa078d49 - by VideoLAN
Error decoding frame: Invalid argument
Error parsing OBU data
Error decoding frame: Invalid argument
Error decoding frame: Invalid argument
Error decoding frame: Invalid argument
No data decoded
---