hwloc: have opal_hwloc_base_get_pu search for HWLOC_OBJ_PU when mpirun is invoked with --use-hwthread-cpus

Fixes open-mpi/ompi#1247

opal/mca/hwloc/base/hwloc_base_util.c

@@ -14,7 +14,7 @@
  * Copyright (c) 2012-2015 Los Alamos National Security, LLC.
  *                         All rights reserved.
  * Copyright (c) 2013-2014 Intel, Inc. All rights reserved.
- * Copyright (c) 2015      Research Organization for Information Science
+ * Copyright (c) 2015-2016 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * $COPYRIGHT$
  *
@@ -71,7 +71,7 @@ hwloc_obj_t opal_hwloc_base_get_pu(hwloc_topology_t topo,
        So first we have to see if we can find *any* cores by looking
        for the 0th core.  If we find it, then try to find the Nth
        core.  Otherwise, try to find the Nth PU. */
-    if (NULL == hwloc_get_obj_by_type(topo, HWLOC_OBJ_CORE, 0)) {
+    if (opal_hwloc_use_hwthreads_as_cpus || (NULL == hwloc_get_obj_by_type(topo, HWLOC_OBJ_CORE, 0))) {
         obj_type = HWLOC_OBJ_PU;
     }