Code style change in unit test for VP8/VP9 denoiser.

Change-Id: If4b0aca18c8474dd2456900ae9681e74222e645f
Remove mi_grid_base_array from VP9_COMMON (unused)

Change-Id: I4b4764463f5a7cdc01ec004b882c6237466c74b0
Refactor rate distortion cost structure

This commit makes a struct that contains rate value, distortion
value, and the rate-distortion cost. The goal is to provide a
better interface for rate-distortion related operation. It is
first used in rd_pick_partition and saves a few RDCOST calculations.

Change-Id: I1a6ab7b35282d3c80195af59b6810e577544691f
Fix vp9_rd_pick_inter/intra function types

The returned value is not used anywhere, hence changing the function
type into void.

Change-Id: I0ece49ed61e7aab6df01140135503ad41d4ef4a4
Use speed feature variable in vp9_rd_pick_inter/intra_mode

Replace repeated fetch cpi->sf with a local sf pointer.

Change-Id: I5a55bba3e1c41fbdbc6ad5f078d2fa49dd95ee67
Merge "Remove mi_grid_base_array from VP9_COMMON (unused)"
Merge "Code style change in unit test for VP8/VP9 denoiser."
Merge "Refactor rate distortion cost structure"
Merge "Fix vp9_rd_pick_inter/intra function types"
Merge "Use speed feature variable in vp9_rd_pick_inter/intra_mode"