Fix the application abort routine so we actually abort

Adding @bureddy 's solution for OSHMEM's global exit when applications are launched directly with srun.

I don't think this is the final solution, but I don't want this to get lost in the shuffle. @jsquyres @miked-mellanox @rhc54 

CMR Trac ticket:
https://svn.open-mpi.org/trac/ompi/ticket/4919