vp9_encoder.c: protect SNPRINT* macros w/CONFIG check
vp9_encoder.c: protect SNPRINT* macros w/CONFIG check

these are only used with CONFIG_INTERNAL_STATS

Change-Id: Ibbcefbdc1db79d93f75e5865289f9960a8c2358a

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