Applied the following patches from the upstream hwloc 1.5 branch after
the v1.5.1 release:

https://svn.open-mpi.org/trac/hwloc/changeset/5054
https://svn.open-mpi.org/trac/hwloc/changeset/4999
https://svn.open-mpi.org/trac/hwloc/changeset/4973
https://svn.open-mpi.org/trac/hwloc/changeset/4915
https://svn.open-mpi.org/trac/hwloc/changeset/4912