The assumption that the high bit is not in use in pointers on any of our
supported platforms was incorrect. A better assumption is that all
ompi_proc_t pointers will be at least 2-byte aligned. This allows us
to use the low bit. To do this we drop the highest bit of the
opal_process_name_t jobid (hope this is ok) and use the low bit to
indicate the proc is really a sentinel.
Signed-off-by: Nathan Hjelm <hjelmn@me.com>