Drop Wiener variance diff scale from 8 to 4
Drop Wiener variance diff scale from 8 to 4

Change-Id: If6df62069c1b30de4d52aba33c20c6e854524905

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