Fix a hang due to a race condition when processes call MPI_Abort. If a process was being forcibly killed instead of reaching the call to "abort", then we would accidentally increment a counter in one place while decrementing a counter in another - thus putting them off when comparing the two. This ensures we only increment the one side, and leave the other alone.
Merge pull request #101 from rhc54/cmr/errhandler-hang

Fix a hang due to a race condition when processes call MPI_Abort.