webmdec: Fix visual studio warnings.
webmdec: Fix visual studio warnings.

Fix a couple of visual studio warnings.

Change-Id: I161edf4b37f5ac2defbe6eb5b7e34d219b1f52d9

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