multimedia/ffmpeg: unbreak SVTVP9=on after 685e477b807c

> Applying distribution patches for ffmpeg-6.0,1

1 out of 1 hunks failed--saving rejects to libavcodec/allcodecs.c.rej
1 out of 3 hunks failed--saving rejects to libavformat/dashenc.c.rej
3 out of 9 hunks failed--saving rejects to libavformat/matroskaenc.c.rej

> FAILED Applying distribution patch master-0001-Add-ability-for-ffmpeg-to-run-svt-vp9.patch with -p1

PR: 261302