avformat/oggparseogm: check input size before reading t

Makes no difference in outcome, as the checks on t have no effect
when t was uninitialized

Fixes use of uninitialized memory
Fixes: msan_uninit-mem_7fa2b7b5d97c_3598_anOTHERS_DixX_in_Ogg_Sample.avi
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/huffyuvdec: clear remainder of the array on end of input in decode_422_bitstream()

Fixes: msan_uninit-mem_7f909423efcd_9923_yuv_predmed.avi
Fixes use of uninitialized memory
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>