kgv1dec: Increase offsets array size so it is large enough.

Fixes CVE-2011-3945

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 807a045ab7f51993a2c1b3116016cbbd4f3d20d6)

Signed-off-by: Alex Converse <alex.converse@gmail.com>
