usnic: make this show_help message like the others

There's no need for the port number (since usNIC has no port numbers),
and make the wording the same as other help messages.

Reviewed by Reese Faucette.

cmr=v1.8.2:reviewer=ompi-rm1.8
usnic: EHOSTUNREACH means there is no route

ibv_create_ah() can also return EHOSTUNREACH, which means that there
is no route to the peer.  Treat that as a non-fatal warning.

Reviewed by Reese Faucette.

cmr=v1.8.2:reviewer=ompi-rm1.8
Silence warning
As discussed at the OMPI developer's meeting, add functions to start, stop, and restart libevent-driven progress threads. Critical NOTE: if you don't have a file descriptor event defined for your progress thread, it will spin hard! Accordingly, the "start progress thread" function has a boolean parameter you can use to request that the function automatically create one for you.
Merge branch 'master' of github.com:open-mpi/ompi-svn-mirror
Reset these files back to match the trunk