[x265] [PATCH] Implementation of low-pass subband dct approximation

[Mont3z Claros]

Hi all,

I've submitted a new patch. I've disabled the low pass dct for the 8x8
blocks. I think this was yielding better quality results and the 8x8
low pass dct was giving less performance gain. I've ran tests with
streams Traffic_2560x1600_30_crop and FourPeople_1280x720_60.

Thanks,
Humberto