Cleaning up read_skip_coeff() function.
Cleaning up read_skip_coeff() function.

Making code easier to read and avoiding calculation of skip context twice.

Change-Id: I42c376b1a1811bc842bf6420bf81d2de7a1bf980

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