Backport of "avdemux: fix build with FFmpeg 4.4" into 1.18
requested to merge tpm/gst-libav:backport-mr-127-into-1.18-avdemux-fix-build-with-ffmpeg-4.4 into 1.18
Backport of !127 (merged) "avdemux: fix build with FFmpeg 4.4".
Commits:
- 07b43c72 avdemux: fix build with FFmpeg 4.4