vp9: Scene cut/slide change detection: Increse min_thresh.
vp9: Scene cut/slide change detection: Increse min_thresh.

Only affects vbr mode.

Change-Id: I15e24c50343bc9171c734dfc7685491c7dbb8654

mbebenita/aom,ShiftMediaProject/libvpx,mwgoldsmith/vpx,ittiamvpx/libvpx-1,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,Topopiccione/libvpx,mbebenita/aom,ittiamvpx/libvpx-1,mwgoldsmith/vpx,luctrudeau/aom,Topopiccione/libvpx,webmproject/libvpx,mwgoldsmith/libvpx,Topopiccione/libvpx,smarter/aom,smarter/aom,mwgoldsmith/libvpx,smarter/aom,luctrudeau/aom,ittiamvpx/libvpx-1,mbebenita/aom,mbebenita/aom,ShiftMediaProject/libvpx,mwgoldsmith/vpx,ittiamvpx/libvpx-1,mbebenita/aom,Topopiccione/libvpx,smarter/aom,luctrudeau/aom,luctrudeau/aom,ittiamvpx/libvpx-1,ShiftMediaProject/libvpx,GrokImageCompression/aom,ittiamvpx/libvpx-1,mbebenita/aom,webmproject/libvpx,smarter/aom,mwgoldsmith/vpx,mwgoldsmith/libvpx,mbebenita/aom,GrokImageCompression/aom,GrokImageCompression/aom,Topopiccione/libvpx,webmproject/libvpx,luctrudeau/aom,luctrudeau/aom,webmproject/libvpx,webmproject/libvpx,GrokImageCompression/aom,GrokImageCompression/aom,webmproject/libvpx,Topopiccione/libvpx,mwgoldsmith/vpx,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,mwgoldsmith/vpx,GrokImageCompression/aom,mwgoldsmith/libvpx,mbebenita/aom,smarter/aom,mbebenita/aom