Fixes: runtime error: index 49 out of bounds for type 'int [48][2][2]'
Fixes: 2159/clusterfuzz-testcase-minimized-5267945972301824

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 3a1ad368a78b153b63ccc07af864b3611e2a4ac3)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>