avutil/audio_fifo: Use av_mallocz_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
tests/tiny_ssim: more correct error message

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

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