lavc: fix forgotten "que" reference.

This should have been part of 491ca0e8.
svq1dec: check that the reference frame matches in size before using it.

Fixes out of array reads

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavf/utils: more complete dts checks

Fixes division by zero

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>