compress/bzip2: use io.ByteReader instead of internal interface
compress/bzip2: use io.ByteReader instead of internal interface

R=golang-dev, bradfitz
CC=golang-dev
http://codereview.appspot.com/6663044

scirelli/scirelli-go,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,scirelli/scirelli-go,mhennings/marcohennings-go,rdp/rogerpack2005-golang,webfd/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,rdp/rogerpack2005-golang,bryanxu/go-zh,mhennings/marcohennings-go,bryanxu/go-zh,d0f/go-zh,d0f/go-zh,rflanagan/reginaldflanagan-project1,webfd/go-zh,bryanxu/go-zh,sanjosh/sanjos100-tipc,rflanagan/reginaldflanagan-project1,rflanagan/reginaldflanagan-project1,rflanagan/reginaldflanagan-project1,rdp/rogerpack2005-golang,scirelli/scirelli-go,mhennings/marcohennings-go,bryanxu/go-zh,rdp/rogerpack2005-golang,webfd/go-zh,scirelli/scirelli-go,mhennings/marcohennings-go,rdp/rogerpack2005-golang,mhennings/marcohennings-go,d0f/go-zh,mhennings/marcohennings-go,sanjosh/sanjos100-tipc,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,webfd/go-zh,bryanxu/go-zh,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,rflanagan/reginaldflanagan-project1,rdp/rogerpack2005-golang,rdp/rogerpack2005-golang,webfd/go-zh,d0f/go-zh,bryanxu/go-zh,bryanxu/go-zh,webfd/go-zh,rflanagan/reginaldflanagan-project1,sanjosh/sanjos100-tipc,d0f/go-zh,sanjosh/sanjos100-tipc,mhennings/marcohennings-go,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,mhennings/marcohennings-go,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc,sanjosh/sanjos100-tipc,scirelli/scirelli-go,rflanagan/reginaldflanagan-project1,scirelli/scirelli-go