tr: use BitvSet instead of HashSet
tr: use BitvSet instead of HashSet

bundai223/coreutils,dbrgn/coreutils,polapl/coreutils,samfoo/coreutils,dennis/coreutils,uutils/coreutils,dbrgn/coreutils,hexsel/coreutils,samfoo/coreutils,retep998/coreutils,hexsel/coreutils,beni55/coreutils,retep998/coreutils,Shir0kamii/coreutils,Arcterus/coreutils,filmor/coreutils,kball/coreutils,dennis/coreutils,keunwoo/coreutils,tempbottle/coreutils,filmor/coreutils,jbcrail/coreutils,Gianbaoluo/coreutils,silvio/rust-coreutils,Shtong/coreutils,Heather/coreutils,uutils/coreutils,steveklabnik/coreutils,steveklabnik/coreutils,silvio/rust-coreutils,dbrgn/coreutils,Shtong/coreutils,sshling/coreutils,ebfe/coreutils,tempbottle/coreutils,jbcrail/coreutils,sshling/coreutils,Arcterus/coreutils,bundai223/coreutils,kball/coreutils,Heather/coreutils,kwantam/coreutils,kwantam/coreutils,Shir0kamii/coreutils,Gianbaoluo/coreutils,kevgeniy/coreutils,wimh/coreutils,keunwoo/coreutils,uutils/coreutils,polapl/coreutils,dokaptur/coreutils,kevgeniy/coreutils,wimh/coreutils,mauricio/coreutils,beni55/coreutils,efuquen/coreutils,mauricio/coreutils,ebfe/coreutils,efuquen/coreutils