Don't use transform domain distortion when eob is 0

Don't use transform domain distortion when eob is 0

When eob is 0, pixel domain distortion is more accurate and efficient.

This mainly affects speed >= 2. Speed 0 always use pixel domain
distortion; speed 1 use it most of the time.

Compression impact(negative means gain):
        speed 2   speed 3   speed 4
lowres   -0.04%   -0.06%    -0.06%
midres   -0.10%   -0.10%    -0.20%
hdres    -0.01%   -0.03%    -0.06%

Encoding speed is about neutral.

Change-Id: I77b957658deeaad57381fd13afc11bacdec8c08f