fix garbage collection race: save stack trace when changing process state to Gsyscall, not after.
fix garbage collection race: save stack trace
when changing process state to Gsyscall, not after.

R=r
DELTA=8  (4 added, 3 deleted, 1 changed)
OCL=30320
CL=30325

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