avcodec/vp9dsp: pass dconly bit as macro argument.
avcodec/hnm4video: check dimensions for validity

Fixes out of array read
Fixes: asan_heap-oob_e76e18_1244_CASSE.HNM
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/hnm: check chunk_size == 0

Fixes potential infinite loop

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/hnm4video: check writeoffset in decode_interframe_v4a()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>