in traceback, handle the case where we've called through a nil function pointer
in traceback, handle the case where we've called through a nil function pointer

R=rsc
DELTA=7  (7 added, 0 deleted, 0 changed)
OCL=18372
CL=18372

mhennings/marcohennings-go,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,Triskite/willstone-goclone,npe9/noahevans-go9,d0f/go-zh,bryanxu/go-zh,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,npe9/noahevans-go9,bryanxu/go-zh,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,scirelli/scirelli-go,Triskite/willstone-goclone,rdp/rogerpack2005-golang,Triskite/willstone-goclone,bryanxu/go-zh,Triskite/willstone-goclone,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,rdp/rogerpack2005-golang,webfd/go-zh,scirelli/scirelli-go,npe9/noahevans-go9,rflanagan/reginaldflanagan-project1,Triskite/willstone-goclone,npe9/noahevans-go9,d0f/go-zh,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,mhennings/marcohennings-go,mhennings/marcohennings-go,scirelli/scirelli-go,d0f/go-zh,npe9/noahevans-go9,rflanagan/reginaldflanagan-project1,mhennings/marcohennings-go,scirelli/scirelli-go,scirelli/scirelli-go,mhennings/marcohennings-go,rdp/rogerpack2005-golang,webfd/go-zh,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,npe9/noahevans-go9,d0f/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,rflanagan/reginaldflanagan-project1,bryanxu/go-zh,d0f/go-zh,Triskite/willstone-goclone,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc,d0f/go-zh,Triskite/willstone-goclone,sanjosh/sanjos100-tipc,Triskite/willstone-goclone,rflanagan/reginaldflanagan-project1,npe9/noahevans-go9,bryanxu/go-zh,rflanagan/reginaldflanagan-project1,mhennings/marcohennings-go,webfd/go-zh,npe9/noahevans-go9,rdp/rogerpack2005-golang,webfd/go-zh,mhennings/marcohennings-go,scirelli/scirelli-go,sanjosh/sanjos100-tipc,rflanagan/reginaldflanagan-project1,sanjosh/sanjos100-tipc,scirelli/scirelli-go,rflanagan/reginaldflanagan-project1