vp9_subtract_test: drop '_t' from local typenames
vp9_subtract_test: drop '_t' from local typenames

_t is reserved by posix

+ switch to camelcase
  http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Type_Names

Change-Id: I636012c74f5de91d594d7398e92343f5efe08327

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