MAINTANERS: update snow/ffv1/nut entries as these are no longer in a single file

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avutil/pca: Use av_malloc_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
swscale/utils: use FF_ALLOC(Z)_ARRAY_OR_GOTO() and av_malloc(z)_array()

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