Fixes #3625: Move r28552 and r28578 to v1.7 Branch

Modified to port patches to the v1.7 branch

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r28551 [[BR]]
Bring over upstream hwloc trunk commit
https://svn.open-mpi.org/trac/hwloc/changeset/5592 to fix the merging
of groups when they are I/O objects.

r28552 [[BR]]
This commit introduces a new "mindist" ORTE RMAPS mapper, as well as
some relevant updates/new functionality in the opal/mca/hwloc and
orte/mca/rmaps bases.  This work was mainly developed by Mellanox,
with a bunch of advice from Ralph Castain, and some minor advice from
Brice Goglin and Jeff Squyres.

Even though this is mainly Mellanox's work, Jeff is committing only
for logistical reasons (he holds the hg+svn combo tree, and can
therefore commit it directly back to SVN).

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Implemented distance-based mapping algorithm as a new "mindist"
component in the rmaps framework.  It allows mapping processes by NUMA
due to PCI locality information as reported by the BIOS - from the
closest to device to furthest.

To use this algorithm, specify:

   {{{mpirun --map-by dist:<device_name>}}}

where <device_name> can be mlx5_0, ib0, etc.

There are two modes provided:

 1. bynode: load-balancing across nodes
 1. byslot: go through slots sequentially (i.e., the first nodes are
     more loaded)

These options are regulated by the optional ''span'' modifier; the
command line parameter looks like:

    {{{mpirun --map-by dist:<device_name>,span}}}

So, for example, if there are 2 nodes, each with 8 cores, and we'd
like to run 10 processes, the mindist algorithm will place 8 processes
to the first node and 2 to the second by default. But if you want to
place 5 processes to each node, you can add a span modifier in your
command line to do that.

If there are two NUMA nodes on the node, each with 4 cores, and we run
6 processes, the mindist algorithm will try to find the NUMA closest
to the specified device, and if successful, it will place 4 processes
on that NUMA but leaving the remaining two to the next NUMA node.

You can also specify the number of cpus per MPI process. This option
is handled so that we map as many processes to the closest NUMA as we
can (number of available processors at the NUMA divided by number of
cpus per rank) and then go on with the next closest NUMA.

The default binding option for this mapping is bind-to-numa. It works
if you don't specify any binding policy. But if you specified binding
level that was "lower" than NUMA (i.e hwthread, core, socket) it would
bind to whatever level you specify.

r28578 [[BR]]
Minor fix for the min-dist mapping algorithm: we need to call 'get_nbobjs_by_type' first, before we get the sorted list of nodes - we need to add node objects and fill them in the summary object for the current topology. This patch was submitted by Elena Elkina and pushed by Josh Ladd. This should be added to cmr:v1.7:reviewer=jladd

r28620 [[BR]]
Stomps compiler warnings in HCA min-dist calculation. This should be added to cmr:v1.7:reviewer=jladd