Let do_motion_search process one ref at at time
Let do_motion_search process one ref at at time

Change-Id: Iee3f2d1fbeddeee27400edb6fe1519c39352901d

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