[petsc-dev] Errors in ThreadComm stuff

[Mark F. Adams]

I'm getting segv in at the end of runs on the Cray XC30.  in optimized builds 
it segv with a stack like

PetscFinalize
PetscViewerASCIIGetStdout
PetscCommDuplicate
PetscThreadCommGetRank

In debug builds it does not segv but there are a bunch of un freeded memory in 
ThreadComm stuff.

Mark