VP8TBufferClear: remove some misleading const's
VP8TBufferClear: remove some misleading const's

the input to the function is non-const and the pointer being operated is
being free'd; removes an unnecessary cast in the process

Change-Id: Ic515ed672ddf7f8e4e36eeac696ff7aa8a3652f7

iniwf/webm.libwebp,matanbs/webm.libwebp,kleopatra999/webm.libwebp,zofuthan/libwebp,jiehu5114/libwebp,imazen/libwebp,gshORTON/webm.libwebp,kleopatra999/webm.libwebp,abwiz0086/webm.libwebp,PKRoma/libwebp,Aexyn/libwebp,Acidburn0zzz/webm.libwebp,ya7lelkom/libwebp,redengineer/libwebp,jacklicn/libwebp,redengineer/libwebp,Maria1099/webm.libwebp,Suvarna1488/webm.libwebp,abwiz0086/webm.libwebp,abwiz0086/webm.libwebp,jiehu5114/libwebp,kalli123/webm.libwebp,ericmckean/webm.libwebp,abwiz0086/webm.libwebp,ericmckean/webm.libwebp,reimaginemedia/webm.libwebp,altogother/webm.libwebp,Maria1099/webm.libwebp,ttyangf/libwebp,Acidburn0zzz/webm.libwebp,rxl194/libwebp,webmproject/libwebp,PKRoma/libwebp,ericmckean/webm.libwebp,yohunl/libwebp,Maria1099/webm.libwebp,webmproject/libwebp,PKRoma/libwebp,redengineer/libwebp,jiehu5114/libwebp,PKRoma/libwebp,ttyangf/libwebp,kim42083/webm.libwebp,ericmckean/webm.libwebp,ericmckean/webm.libwebp,kalli123/webm.libwebp,gshORTON/webm.libwebp,ttyangf/libwebp,PKRoma/libwebp,zofuthan/libwebp,Maria1099/webm.libwebp,Aexyn/libwebp,altogother/webm.libwebp,yohunl/libwebp,yohunl/libwebp,kleopatra999/webm.libwebp,iniwf/webm.libwebp,Acidburn0zzz/webm.libwebp,ttyangf/libwebp,Aexyn/libwebp,zofuthan/libwebp,imazen/libwebp,jacklicn/libwebp,reimaginemedia/webm.libwebp,redengineer/libwebp,ttyangf/libwebp,gshORTON/webm.libwebp,webmproject/libwebp,rxl194/libwebp,kleopatra999/webm.libwebp,altogother/webm.libwebp,jacklicn/libwebp,jacklicn/libwebp,iniwf/webm.libwebp,rxl194/libwebp,zofuthan/libwebp,Suvarna1488/webm.libwebp,kim42083/webm.libwebp,reimaginemedia/webm.libwebp,Aexyn/libwebp,ya7lelkom/libwebp,jiehu5114/libwebp,kalli123/webm.libwebp,iniwf/webm.libwebp,abwiz0086/webm.libwebp,kleopatra999/webm.libwebp,Suvarna1488/webm.libwebp,reimaginemedia/webm.libwebp,matanbs/webm.libwebp,zofuthan/libwebp,matanbs/webm.libwebp,iniwf/webm.libwebp,rxl194/libwebp,Aexyn/libwebp,jiehu5114/libwebp,redengineer/libwebp,PKRoma/libwebp,imazen/libwebp,ya7lelkom/libwebp,altogother/webm.libwebp,imazen/libwebp,ya7lelkom/libwebp,reimaginemedia/webm.libwebp,gshORTON/webm.libwebp,kalli123/webm.libwebp,rxl194/libwebp,kim42083/webm.libwebp,Suvarna1488/webm.libwebp,yohunl/libwebp,altogother/webm.libwebp,matanbs/webm.libwebp,kim42083/webm.libwebp,gshORTON/webm.libwebp,webmproject/libwebp,Maria1099/webm.libwebp,Acidburn0zzz/webm.libwebp,ya7lelkom/libwebp,webmproject/libwebp,jacklicn/libwebp,kalli123/webm.libwebp,Suvarna1488/webm.libwebp,kim42083/webm.libwebp,yohunl/libwebp,imazen/libwebp,matanbs/webm.libwebp,Acidburn0zzz/webm.libwebp