Always initialize values in sb/mb_partitioning.
Always initialize values in sb/mb_partitioning.

This doesn't affect the output, because in previous cases where the
values were uninitialized, this was because the mb_row/col is outside
the codable area, and thus encode_sb will test them for the next
decomposition-level, but return right after that on size-check. All
this does is prevent a warning in valgrind.

Change-Id: I90d8a29e6f8ebb2b0143684e08fe77ae3a0816b1

jdm/libvpx,WebRTC-Labs/libvpx,jacklicn/webm.libvpx,VTCSecureLLC/libvpx,matanbs/webm.libvpx,VTCSecureLLC/libvpx,sanyaade-teachings/libvpx,running770/libvpx,WebRTC-Labs/libvpx,luctrudeau/aom,cinema6/libvpx,jacklicn/webm.libvpx,lyx2014/libvpx_c,shyamalschandra/libvpx,pcwalton/libvpx,matanbs/webm.libvpx,shareefalis/libvpx,lyx2014/libvpx_c,luctrudeau/aom,cinema6/libvpx,zofuthan/libvpx,reimaginemedia/webm.libvpx,Suvarna1488/webm.libvpx,Topopiccione/libvpx,shyamalschandra/libvpx,Distrotech/libvpx,shacklettbp/aom,shyamalschandra/libvpx,WebRTC-Labs/libvpx,ittiamvpx/libvpx-1,ittiamvpx/libvpx-1,Acidburn0zzz/webm.libvpx,jdm/libvpx,VTCSecureLLC/libvpx,hsueceumd/test_hui,sanyaade-teachings/libvpx,jdm/libvpx,Acidburn0zzz/webm.libvpx,liqianggao/libvpx,iniwf/webm.libvpx,n4t/libvpx,hsueceumd/test_hui,Laknot/libvpx,n4t/libvpx,Maria1099/webm.libvpx,reimaginemedia/webm.libvpx,altogother/webm.libvpx,Acidburn0zzz/webm.libvpx,smarter/aom,reimaginemedia/webm.libvpx,turbulenz/libvpx,stewnorriss/libvpx,kalli123/webm.libvpx,iniwf/webm.libvpx,kim42083/webm.libvpx,Suvarna1488/webm.libvpx,running770/libvpx,jmvalin/aom,abwiz0086/webm.libvpx,zofuthan/libvpx,iniwf/webm.libvpx,matanbs/vp982,kleopatra999/webm.libvpx,charup/https---github.com-webmproject-libvpx-,shareefalis/libvpx,matanbs/vp982,turbulenz/libvpx,stewnorriss/libvpx,lyx2014/libvpx_c,reimaginemedia/webm.libvpx,GrokImageCompression/aom,jmvalin/aom,goodleixiao/vpx,mbebenita/aom,kleopatra999/webm.libvpx,running770/libvpx,mwgoldsmith/vpx,Maria1099/webm.libvpx,matanbs/vp982,felipebetancur/libvpx,Topopiccione/libvpx,shyamalschandra/libvpx,kleopatra999/webm.libvpx,matanbs/vp982,ittiamvpx/libvpx,smarter/aom,mbebenita/aom,running770/libvpx,pcwalton/libvpx,thdav/aom,sanyaade-teachings/libvpx,openpeer/libvpx_new,goodleixiao/vpx,smarter/aom,pcwalton/libvpx,charup/https---github.com-webmproject-libvpx-,luctrudeau/aom,cinema6/libvpx,VTCSecureLLC/libvpx,mwgoldsmith/libvpx,jmvalin/aom,openpeer/libvpx_new,smarter/aom,stewnorriss/libvpx,webmproject/libvpx,liqianggao/libvpx,running770/libvpx,goodleixiao/vpx,jdm/libvpx,openpeer/libvpx_new,altogother/webm.libvpx,Laknot/libvpx,matanbs/vp982,jacklicn/webm.libvpx,Topopiccione/libvpx,VTCSecureLLC/libvpx,kleopatra999/webm.libvpx,altogother/webm.libvpx,iniwf/webm.libvpx,hsueceumd/test_hui,turbulenz/libvpx,mwgoldsmith/libvpx,jmvalin/aom,hsueceumd/test_hui,Laknot/libvpx,mwgoldsmith/vpx,WebRTC-Labs/libvpx,altogother/webm.libvpx,charup/https---github.com-webmproject-libvpx-,n4t/libvpx,turbulenz/libvpx,Distrotech/libvpx,mwgoldsmith/vpx,cinema6/libvpx,ShiftMediaProject/libvpx,Acidburn0zzz/webm.libvpx,webmproject/libvpx,luctrudeau/aom,abwiz0086/webm.libvpx,Distrotech/libvpx,kim42083/webm.libvpx,Maria1099/webm.libvpx,mbebenita/aom,lyx2014/libvpx_c,turbulenz/libvpx,matanbs/vp982,openpeer/libvpx_new,stewnorriss/libvpx,mwgoldsmith/libvpx,Suvarna1488/webm.libvpx,ittiamvpx/libvpx,gshORTON/webm.libvpx,thdav/aom,matanbs/webm.libvpx,gshORTON/webm.libvpx,Topopiccione/libvpx,ittiamvpx/libvpx,lyx2014/libvpx_c,jdm/libvpx,cinema6/libvpx,liqianggao/libvpx,Laknot/libvpx,gshORTON/webm.libvpx,goodleixiao/vpx,cinema6/libvpx,jmvalin/aom,shacklettbp/aom,felipebetancur/libvpx,kalli123/webm.libvpx,jacklicn/webm.libvpx,smarter/aom,Acidburn0zzz/webm.libvpx,ittiamvpx/libvpx-1,Laknot/libvpx,gshORTON/webm.libvpx,gshORTON/webm.libvpx,mwgoldsmith/vpx,charup/https---github.com-webmproject-libvpx-,ShiftMediaProject/libvpx,mbebenita/aom,felipebetancur/libvpx,Topopiccione/libvpx,thdav/aom,liqianggao/libvpx,ShiftMediaProject/libvpx,stewnorriss/libvpx,ShiftMediaProject/libvpx,Distrotech/libvpx,mwgoldsmith/libvpx,pcwalton/libvpx,shyamalschandra/libvpx,ittiamvpx/libvpx-1,Distrotech/libvpx,shacklettbp/aom,mbebenita/aom,GrokImageCompression/aom,turbulenz/libvpx,kim42083/webm.libvpx,WebRTC-Labs/libvpx,smarter/aom,matanbs/webm.libvpx,webmproject/libvpx,kalli123/webm.libvpx,matanbs/webm.libvpx,felipebetancur/libvpx,ittiamvpx/libvpx,Maria1099/webm.libvpx,iniwf/webm.libvpx,luctrudeau/aom,pcwalton/libvpx,jacklicn/webm.libvpx,stewnorriss/libvpx,GrokImageCompression/aom,charup/https---github.com-webmproject-libvpx-,mwgoldsmith/libvpx,zofuthan/libvpx,felipebetancur/libvpx,shacklettbp/aom,gshORTON/webm.libvpx,felipebetancur/libvpx,ittiamvpx/libvpx-1,openpeer/libvpx_new,matanbs/webm.libvpx,webmproject/libvpx,Suvarna1488/webm.libvpx,cinema6/libvpx,turbulenz/libvpx,shyamalschandra/libvpx,mbebenita/aom,kalli123/webm.libvpx,running770/libvpx,Maria1099/webm.libvpx,goodleixiao/vpx,kleopatra999/webm.libvpx,mwgoldsmith/vpx,openpeer/libvpx_new,GrokImageCompression/aom,turbulenz/libvpx,thdav/aom,shareefalis/libvpx,zofuthan/libvpx,kalli123/webm.libvpx,altogother/webm.libvpx,reimaginemedia/webm.libvpx,GrokImageCompression/aom,zofuthan/libvpx,reimaginemedia/webm.libvpx,shareefalis/libvpx,kim42083/webm.libvpx,webmproject/libvpx,n4t/libvpx,kim42083/webm.libvpx,GrokImageCompression/aom,kleopatra999/webm.libvpx,lyx2014/libvpx_c,goodleixiao/vpx,abwiz0086/webm.libvpx,ittiamvpx/libvpx,VTCSecureLLC/libvpx,mwgoldsmith/vpx,abwiz0086/webm.libvpx,jmvalin/aom,ittiamvpx/libvpx,sanyaade-teachings/libvpx,abwiz0086/webm.libvpx,iniwf/webm.libvpx,shareefalis/libvpx,thdav/aom,altogother/webm.libvpx,shacklettbp/aom,Laknot/libvpx,mwgoldsmith/libvpx,matanbs/vp982,Topopiccione/libvpx,mbebenita/aom,kalli123/webm.libvpx,jdm/libvpx,mbebenita/aom,shacklettbp/aom,Acidburn0zzz/webm.libvpx,hsueceumd/test_hui,webmproject/libvpx,shareefalis/libvpx,Suvarna1488/webm.libvpx,kim42083/webm.libvpx,Suvarna1488/webm.libvpx,turbulenz/libvpx,ittiamvpx/libvpx-1,abwiz0086/webm.libvpx,Distrotech/libvpx,ShiftMediaProject/libvpx,luctrudeau/aom,zofuthan/libvpx,charup/https---github.com-webmproject-libvpx-,hsueceumd/test_hui,pcwalton/libvpx,sanyaade-teachings/libvpx,liqianggao/libvpx,mbebenita/aom,liqianggao/libvpx,thdav/aom,Maria1099/webm.libvpx,jacklicn/webm.libvpx,n4t/libvpx