Fixes: signal_sigabrt_7ffff70eccc9_498_divx502.avi with memlimit 1572864

Found-by: Samuel Groß, Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 2ea8a480

)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>