ompi_mtl_portals4_get_endpoint() was incorrectly making a direct
call to ompi_mtl_portals4_add_procs(). Instead use the actve PML
to call add_procs(). If add_procs() fails, call ompi_rte_abort()
to terminate the job.
Signed-off-by: Todd Kordenbrock <thkgcode@gmail.com>