cmd/yacc: always import fmt, safely The parser depends on it but the client might not import it, so make sure it's there. Fixes issue 4038.
cmd/yacc: always import fmt, safely
The parser depends on it but the client might not import it, so make sure it's there.
Fixes issue 4038.

R=golang-dev, rsc
CC=golang-dev
http://codereview.appspot.com/6497094

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