runtime: fix bug in tracebacks Need to correct for deferproc's extra 2 words of stack or in some cases (such as memory profiling) traceback can cause a crash. Also bulletproof the closure test.
runtime: fix bug in tracebacks
Need to correct for deferproc's extra 2 words of stack or in some
cases (such as memory profiling) traceback can cause a crash.
Also bulletproof the closure test.

R=rsc
CC=golang-dev
http://codereview.appspot.com/2138047

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