Fixes #4452: Move r31225 to v1.8 branch (usnic: drop unknown connection checker)

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r31225 [[BR]]
usnic: drop unknown connection checker packets without erroring out

In most cases, bad messages received by the connectivty checker are
just dropped.  However, in one specific code path, a bad packet caused
an abort.  Doh!

This commit does two things:

1. Improve verbose messages for all these cases
1. Simply drop incoming messages that cannot be identified as ACKs or PINGs

Submitted by Jeff Squyres, reviewed by Dave Goodell.

cmr=v1.8:reviewer=ompi-rm1.8
Fixes #4396: Move r31074 to v1.8 branch (Fix minor hwloc memory leak)

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r31074 [[BR]]
Fix minor hwloc memory leak in sbgp/basesmsocket

cmr=v1.8:reviewer=hjelmn