Don't warn about binding (process and/or memory) if the node cannot do it or if we would overload, but it wasn't specifically requested by the user (i.e., it is the result of the default policy). Instead, just don't bind and quietly move along.

Reset topology usage for each node as we bind as multiple nodes may be linked to the same topology object. This will need to be revisited for scale as it does take some non-zero time to reset the usage each iteration. However, storing individual topology objects for every node consumes memory, so it's a tradeoff.

cmr=v1.7.4:reviewer=jsquyres:subject=Eliminate excessive binding/memory warnings
Fixes #3990: ensure we don't SIGBUS on SPARC by forcing a memory copy
and preventing access to potentially unaligned data.

Reviewed by Dave Goodell.  Tested by Siegmarr Gross.

cmr=v1.7.4:reviewer=ompi-rm1.7:subject=fix SPARC SIGBUS in opal net code