Fixes:
https://fate.ffmpeg.org/report.cgi?slot=x86_64-archlinux-gcc-tsan&time=20240823175808
Reproduction steps:
./configure --enable-memory-poisoning --toolchain=gcc-tsan --disable-stripping && make fate-vvc
Root cause:
We hold the current frame's lock while updating progress for other frames,
which also requires acquiring other frame locks. This could potentially lead to a deadlock.
However, I don't think this will happen in practice because progress updates are one-way, with no cyclic dependencies.
But we need this patch to make FATE happy.