Fixes out of array access
Fixes: asan_heap-oob_12a55d3_30_029.wmv
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 32e666c3)

Conflicts:

	libavcodec/g2meet.c