Optimize RDMult

Optimize RDMult

This commit introduces the optimized RDMult values for both key
and non-key frames. For key frames, the commit gets values back
from commit#b13f6154df9c0834d74f7e3d41e41c4208f56d18. For impact
on key frame only encodings, see commit message for that commit.

For inter frames, the values get optimzied by running encoding tests
in Q mode with the following range using 150 frames:
2 6 10 14 18 22 26 30 34 38 42 46 50 54 58 62

The impact of current set of RDMULT values:
           PSNR     SSIM     PSNR-HVS
lowres:  -0.325%   0.422%    -0.228%
midres:  -0.377%   0.158%    -0.376%
hdres:   -0.309%   0.522%    -0.322%

Test baseline is on commit#35617458

Overall, the values help PSNR based metrics, but hurt SSIM metric
slightly.

Change-Id: I7eba37a6524cb36b8498a1d104d2667781bc2089