Fix uninitialized mesh feature for BEST mode

Fix uninitialized mesh feature for BEST mode

At BEST encoding mode, the mesh search range wasn't initialized for
non FC_GRAPHICS_ANIMATION content type, which actually/mistakenly
used speed 0's setting. Fixed it by adding the initialization.

There were 2 ways to fix this. Patchset 1 set to use speed 0's setting
for non FC_GRAPHICS_ANIMATION type. This didn't change BEST mode's
encoding results much, and only a couple of clips' results were changed.

Borg result for BEST mode:
         avg_psnr:  ovr_psnr:  ssim:  encoding_spdup:
lowres2:  -0.004     -0.003   -0.000    0.030
midres2:  -0.006     -0.009   -0.012    0.033
hdres2:    0.002      0.002    0.004    0.015

Patchset 2 set to use BEST's setting for non FC_GRAPHICS_ANIMATION type.
However, the majority of test clips' BDrate got changed up to
~0.5% (gain or loss), and overall it didn't give better performance
than patchset 1. So, we chose to use patchset 1.

Change-Id: Ibbf578dad04420e6ba22cb9a3ddec137a7e4deef