avfilter/vf_unsharp: use av_malloc_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/vf_dejudder: Use av_mallocz_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/formats: Use av_realloc_array()

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