vp8: Adjust threshold to set the gf_noboost flag.
vp8: Adjust threshold to set the gf_noboost flag.

Change only affects 1 pass cbr, with error_resilient off.

Change-Id: Ibf254d8772fa2a8f188c9932d37b2f42362d8003

webmproject/libvpx,mwgoldsmith/libvpx,mwgoldsmith/libvpx,Topopiccione/libvpx,Topopiccione/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/vpx,mwgoldsmith/libvpx,webmproject/libvpx,Topopiccione/libvpx,Topopiccione/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,Topopiccione/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,Topopiccione/libvpx,webmproject/libvpx,mwgoldsmith/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,mwgoldsmith/libvpx,mwgoldsmith/vpx,mwgoldsmith/vpx,mwgoldsmith/vpx,mwgoldsmith/vpx,mwgoldsmith/vpx