Add data structure for frame dependent mode decision
Add data structure for frame dependent mode decision

Add block and frame level data structures to support frame
dependent mode decision.

Change-Id: I996fc84155fcba8e2ec2a114bb0799d6aa5539dd

ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx