gc: use octal escapes in mkopnames
gc: use octal escapes in mkopnames

Plan 9's tr(1) doesn't accept the C-style escapes
for tab and newline characters.  I was going to use
the \xFF hexadecimal escapes but GNU tr(1) doesn't
accept those.  It seems octal is the least common
denominator.

R=golang-dev, rsc
CC=golang-dev
http://codereview.appspot.com/5576079

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