Propagate macroblock MV to subblocks for error concealment
Propagate macroblock MV to subblocks for error concealment

EC expects the subblock MVs to be populated, but
f1d6cc79e43f0066632f19c1854ca365086b712b removed this code. This
commit restores it, protected by CONFIG_ERROR_CONCEALMENT. May move this
to the EC code more directly in the future.

Change-Id: I44f8f985720cb9a1bf222e59143f9e69abf56ad2

shacklettbp/aom,Distrotech/libvpx,awatry/libvpx.opencl,n4t/libvpx,vasilvv/esvp8,thdav/aom,mwgoldsmith/libvpx,iniwf/webm.libvpx,abwiz0086/webm.libvpx,Laknot/libvpx,lyx2014/libvpx_c,mwgoldsmith/libvpx,gshORTON/webm.libvpx,luctrudeau/aom,ShiftMediaProject/libvpx,genesi/libvpx0,running770/libvpx,hsueceumd/test_hui,reimaginemedia/webm.libvpx,felipebetancur/libvpx,jmvalin/aom,kleopatra999/webm.libvpx,shyamalschandra/libvpx,hsueceumd/test_hui,cinema6/libvpx,Acidburn0zzz/webm.libvpx,altogother/webm.libvpx,shacklettbp/aom,thdav/aom,hsueceumd/test_hui,altogother/webm.libvpx,genesi/libvpx0,Topopiccione/libvpx,vasilvv/esvp8,jmvalin/aom,VTCSecureLLC/libvpx,Distrotech/libvpx,webmproject/libvpx,vasilvv/esvp8,gshORTON/webm.libvpx,kleopatra999/webm.libvpx,pcwalton/libvpx,luctrudeau/aom,gshORTON/webm.libvpx,matanbs/webm.libvpx,mbebenita/aom,kalli123/webm.libvpx,shareefalis/libvpx,zofuthan/libvpx,mbebenita/aom,reimaginemedia/webm.libvpx,jmvalin/aom,WebRTC-Labs/libvpx,liqianggao/libvpx,smarter/aom,mwgoldsmith/libvpx,kleopatra999/webm.libvpx,running770/libvpx,webmproject/libvpx,WebRTC-Labs/libvpx,ittiamvpx/libvpx-1,Maria1099/webm.libvpx,kim42083/webm.libvpx,lyx2014/libvpx_c,mwgoldsmith/vpx,cinema6/libvpx,lyx2014/libvpx_c,smarter/aom,Topopiccione/libvpx,WebRTC-Labs/libvpx,matanbs/vp982,liqianggao/libvpx,GrokImageCompression/aom,mwgoldsmith/vpx,openpeer/libvpx_new,stewnorriss/libvpx,Maria1099/webm.libvpx,felipebetancur/libvpx,charup/https---github.com-webmproject-libvpx-,Laknot/libvpx,abwiz0086/webm.libvpx,jdm/libvpx,VTCSecureLLC/libvpx,webmproject/libvpx,reimaginemedia/webm.libvpx,kalli123/webm.libvpx,matanbs/webm.libvpx,mbebenita/aom,liqianggao/libvpx,reimaginemedia/webm.libvpx,Suvarna1488/webm.libvpx,altogother/webm.libvpx,turbulenz/libvpx,turbulenz/libvpx,charup/https---github.com-webmproject-libvpx-,jacklicn/webm.libvpx,sanyaade-teachings/libvpx,luctrudeau/aom,mbebenita/aom,turbulenz/libvpx,awatry/libvpx.opencl,ittiamvpx/libvpx,jdm/libvpx,mwgoldsmith/libvpx,cinema6/libvpx,ittiamvpx/libvpx,jdm/libvpx,matanbs/vp982,felipebetancur/libvpx,awatry/libvpx.opencl,jacklicn/webm.libvpx,luctrudeau/aom,lyx2014/libvpx_c,kalli123/webm.libvpx,kim42083/webm.libvpx,mwgoldsmith/vpx,smarter/aom,thdav/aom,Topopiccione/libvpx,ittiamvpx/libvpx,ittiamvpx/libvpx,lyx2014/libvpx_c,Acidburn0zzz/webm.libvpx,zofuthan/libvpx,Topopiccione/libvpx,shareefalis/libvpx,ShiftMediaProject/libvpx,gshORTON/webm.libvpx,matanbs/vp982,goodleixiao/vpx,VTCSecureLLC/libvpx,kalli123/webm.libvpx,running770/libvpx,zofuthan/libvpx,openpeer/libvpx_new,shacklettbp/aom,kim42083/webm.libvpx,goodleixiao/vpx,mbebenita/aom,sanyaade-teachings/libvpx,thdav/aom,mwgoldsmith/vpx,webmproject/libvpx,abwiz0086/webm.libvpx,cinema6/libvpx,cinema6/libvpx,pcwalton/libvpx,altogother/webm.libvpx,vasilvv/esvp8,Suvarna1488/webm.libvpx,n4t/libvpx,running770/libvpx,shacklettbp/aom,shyamalschandra/libvpx,Maria1099/webm.libvpx,ShiftMediaProject/libvpx,luctrudeau/aom,shacklettbp/aom,matanbs/vp982,mwgoldsmith/vpx,ittiamvpx/libvpx,Maria1099/webm.libvpx,kim42083/webm.libvpx,Maria1099/webm.libvpx,GrokImageCompression/aom,sanyaade-teachings/libvpx,turbulenz/libvpx,mbebenita/aom,shareefalis/libvpx,jacklicn/webm.libvpx,matanbs/webm.libvpx,felipebetancur/libvpx,matanbs/webm.libvpx,shyamalschandra/libvpx,zofuthan/libvpx,stewnorriss/libvpx,jmvalin/aom,felipebetancur/libvpx,Laknot/libvpx,Suvarna1488/webm.libvpx,mwgoldsmith/vpx,genesi/libvpx0,jacklicn/webm.libvpx,iniwf/webm.libvpx,mbebenita/aom,mbebenita/aom,jmvalin/aom,Topopiccione/libvpx,turbulenz/libvpx,pcwalton/libvpx,goodleixiao/vpx,Acidburn0zzz/webm.libvpx,smarter/aom,genesi/libvpx0,ittiamvpx/libvpx-1,jdm/libvpx,goodleixiao/vpx,liqianggao/libvpx,sanyaade-teachings/libvpx,rikaunite/gst-opera_libvpx,stewnorriss/libvpx,ShiftMediaProject/libvpx,turbulenz/libvpx,GrokImageCompression/aom,Laknot/libvpx,openpeer/libvpx_new,altogother/webm.libvpx,liqianggao/libvpx,smarter/aom,mwgoldsmith/libvpx,running770/libvpx,kim42083/webm.libvpx,VTCSecureLLC/libvpx,Acidburn0zzz/webm.libvpx,cinema6/libvpx,shyamalschandra/libvpx,WebRTC-Labs/libvpx,genesi/libvpx0,shareefalis/libvpx,iniwf/webm.libvpx,n4t/libvpx,kalli123/webm.libvpx,webmproject/libvpx,smarter/aom,shareefalis/libvpx,openpeer/libvpx_new,Topopiccione/libvpx,kim42083/webm.libvpx,thdav/aom,charup/https---github.com-webmproject-libvpx-,awatry/libvpx.opencl,kleopatra999/webm.libvpx,gshORTON/webm.libvpx,turbulenz/libvpx,vasilvv/esvp8,genesi/libvpx0,stewnorriss/libvpx,felipebetancur/libvpx,rikaunite/gst-opera_libvpx,lyx2014/libvpx_c,matanbs/vp982,n4t/libvpx,n4t/libvpx,VTCSecureLLC/libvpx,GrokImageCompression/aom,shacklettbp/aom,zofuthan/libvpx,running770/libvpx,shareefalis/libvpx,rikaunite/gst-opera_libvpx,matanbs/webm.libvpx,liqianggao/libvpx,shyamalschandra/libvpx,hsueceumd/test_hui,jdm/libvpx,charup/https---github.com-webmproject-libvpx-,zofuthan/libvpx,turbulenz/libvpx,gshORTON/webm.libvpx,jmvalin/aom,charup/https---github.com-webmproject-libvpx-,Distrotech/libvpx,Acidburn0zzz/webm.libvpx,Distrotech/libvpx,ittiamvpx/libvp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