dav1d errors while decoding tiles
When running dav1d in single-threadded mode under Fex, it reliably errors out at around frame 121 of the linked test file.

```
dav1d 0.8.1 - by VideoLAN
Decoded 121/8929 frames (1.4%) - 16.42/1784.02 fps (0.01x)Error decoding frame: Invalid argument
```

I've traced the error to this line of code, which is failing an error check, but it's not the source of the error:
https://code.videolan.org/videolan/dav1d/-/blob/2e73051c57a1b2c28c46f72f9edec62f299ebac5/src/decode.c#L2542

It hits the same error in multithreadding mode too, but due to [bugs in dav1d](https://code.videolan.org/videolan/dav1d/-/issues/277) it suppresses the error and just returns invalid results. (Or deadlocks when run under current versions of fex, but that might be a bug in dav1d)  

The real error might be from a frame or two eariler, I've noticed that it slows down while decoding frame 121.

it also fails with `-c irjit -n1` and `-c irint -n 500`.  I suspect this might be an issue in syscall emulation, or maybe a bug in a single instruction.

## Steps to reproduce:

Download the Chimera-AV1-8bit-1920x1080-6736kbps.ivf test file from netflix: http://download.opencontent.netflix.com/?prefix=AV1/Chimera/Old/

Run with the following Command line:   
`FEXLoader -t 1  -- dav1d --framethreads 1 --tilethreads 1 -i Chimera-AV1-8bit-1920x1080-6736kbps.ivf -o test.md5`