Fix tiny_psnr so it compares all bytes (it did skip the last block).

Also display both file sizes and slightly change the output formatting.
[not split in 3 patches to avoid the huge checksum files from being changed
 and having to be reviewed 3 times, if people want it split i can revert and
 split it]

Originally committed as revision 14374 to svn://svn.ffmpeg.org/ffmpeg/trunk