[FFmpeg-cvslog] avformat/mov: ensure all items id referenced by a grid are valid

ffmpeg | branch: release/7.0 | James Almer | Mon Apr 1 21:13:04 2024 -0300| [2ecaef745556684ba3d446994a570214e6fac7ce] | committer: James Almer avformat/mov: ensure all items id referenced by a grid are valid Fixes: null pointer dereference Fixes: 67494/clusterfuzz-testcase-minimized-ffmpeg_

[FFmpeg-cvslog] avformat/mov: ensure all items id referenced by a grid are valid

ffmpeg | branch: master | James Almer | Mon Apr 1 21:13:04 2024 -0300| [f492f1ac239da07970c363fb8c7f7a1aa5b5002a] | committer: James Almer avformat/mov: ensure all items id referenced by a grid are valid Fixes: null pointer dereference Fixes: 67494/clusterfuzz-testcase-minimized-ffmpeg_DEMUXE