avcodec/h264: do proper cleanup in ff_h264_alloc_tables() in case DPB alloc fails

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/h264_slice: More complete cleanup in h264_slice_header_init()

Fixes null pointer dereference
Fixes Ticket3873

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/showcqt: add fontcolor option
avutil/pixelutils: faster pixelutils_sad_[au]_16x16

~560 → ~500 decicycles

This is following the comments from Michael in
https://ffmpeg.org/pipermail/ffmpeg-devel/2014-August/160599.html

Using 2 registers for accumulator didn't help. On the other hand,
some re-ordering between the movs and psadbw allowed going ~538 to ~500.