Update the ompi_info man page with information about variable levels
and improve the behavior of ompi_info.

This commit changes the default behavior of ompi_info --all when a
level is not specified. Instead of assuming level 1 in this case we
now assume level 9. This change is due to feedback from the community
after the introduction of the --level option.

I also added a new option: --selected-only. This option will limit the
displayed variables to components that can be selected (ie. if there
is a selection parameter set-- btl self,sm)

cmr=v1.7.3:reviewer=jsquyres
Also check for /dev/mic/scif when deciding whether to enable the Linux
memory hooks.

The MIC has a /dev/scif device and the host has /dev/mic/scif. I do not
know if this device exists when no MIC is connected.

cmr=v1.7.4:ticket=#3733:reviewer=jsquyres
Replace missing opal_db open/select that was apparently lost on a prior merge. Thanks to Nathan for pointing it out