Use the pred_mv feature for speed 0

Before this patch, pred_mv is used only when the
adaptive_motion_search speed feature is on(speed>=1).
This patch enables pred_mv for speed 0 as well.

Coding gains:
         avg_psnr   ovr_psnr   ssim
lowres   -0.31%     -0.32%    -0.38%
midres   -0.37%     -0.41%    -0.42%
hdres    -0.30%     -0.31%    -0.29%

Tested encoding speed over 18 midres sequences with QP=40. The
overall speed loss is about 0.6%.

Change-Id: I8987e9efb5a70d2bf8779fc2a43838009f9bbd8a
3 files changed