[OpenMP] libomp cleanup: check presence of hwloc objects CORE, PACKAGE

[AndreyChurbanov]

Summary

hwloc documentation guarantees the only object that is always present
in topology is PU. We can check the presence of other objects in the topology
just in case.

[hbae]

LGTM.

openmp/runtime/src/kmp_affinity.cpp

static int __kmp_affinity_create_hwloc_map(AddrUnsPair **address2os,
   KMP_CPU_ALLOC(oldMask);
   __kmp_get_system_affinity(oldMask, TRUE);
   __kmp_hwloc_check_numa();
 
   if (!KMP_AFFINITY_CAPABLE()) {
     // Hack to try and infer the machine topology using only the data
     // available from cpuid on the current thread, and __kmp_xproc.
     KMP_ASSERT(__kmp_affinity_type == affinity_none);
-
-    nCoresPerPkg = __kmp_hwloc_get_nobjs_under_obj(
-        hwloc_get_obj_by_type(tp, HWLOC_OBJ_PACKAGE, 0), HWLOC_OBJ_CORE);
-    __kmp_nThreadsPerCore = __kmp_hwloc_get_nobjs_under_obj(
-        hwloc_get_obj_by_type(tp, HWLOC_OBJ_CORE, 0), HWLOC_OBJ_PU);
+    // hwloc only guarantees existance of PU object, so check PACKAGE and CORE
+    hwloc_obj_t o = hwloc_get_obj_by_type(tp, HWLOC_OBJ_PACKAGE, 0);
+    if (o != NULL)
+      nCoresPerPkg = __kmp_hwloc_get_nobjs_under_obj(o, HWLOC_OBJ_CORE);
+    else
+      nCoresPerPkg = 1; // no PACKAGE found
+    o = hwloc_get_obj_by_type(tp, HWLOC_OBJ_CORE, 0);
+    if (o != NULL)
+      __kmp_nThreadsPerCore = __kmp_hwloc_get_nobjs_under_obj(o, HWLOC_OBJ_PU);
+    else
+      __kmp_nThreadsPerCore = 1; // no CORE found
     __kmp_ncores = __kmp_xproc / __kmp_nThreadsPerCore;
     nPackages = (__kmp_xproc + nCoresPerPkg - 1) / nCoresPerPkg;
     if (__kmp_affinity_verbose) {
       KMP_INFORM(AffNotCapableUseLocCpuidL11, "KMP_AFFINITY");
       KMP_INFORM(AvailableOSProc, "KMP_AFFINITY", __kmp_avail_proc);
       if (__kmp_affinity_uniform_topology()) {
         KMP_INFORM(Uniform, "KMP_AFFINITY");
       } else {