Fixed build warning with -DLIBOMP_USE_HWLOC=1

[AndreyChurbanov]

Summary

HWLOC 2.0 changed the type depth field in hwloc_obj_t structure from unsigned to int. People can use either old or newer HWLOC during the build with -DLIBOMP_USE_HWLOC=1 option. The patch checks the version of HWLOC installed and use appropriate type to prevent build warning on signed-unsigned comparison.

[hbae]

LGTM.

runtime/src/kmp.h

 #if KMP_USE_HWLOC && KMP_AFFINITY_SUPPORTED
 #include "hwloc.h"
 #ifndef HWLOC_OBJ_NUMANODE
 #define HWLOC_OBJ_NUMANODE HWLOC_OBJ_NODE
 #endif
 #ifndef HWLOC_OBJ_PACKAGE
 #define HWLOC_OBJ_PACKAGE HWLOC_OBJ_SOCKET
 #endif
+#if HWLOC_API_VERSION >= 0x00020000
+// hwloc 2.0 changed type of depth of object from unsigned to int
+typedef int kmp_hwloc_depth_t;
+#else
+typedef unsigned int kmp_hwloc_depth_t;
+#endif
 #endif
 
 #if KMP_ARCH_X86 || KMP_ARCH_X86_64
 #include <xmmintrin.h>
 #endif
 
 #include "kmp_debug.h"
 #include "kmp_lock.h"

runtime/src/kmp_affinity.cpp

for (first = hwloc_get_obj_below_by_type(__kmp_hwloc_topology, obj->type,
        first = hwloc_get_next_obj_by_type(__kmp_hwloc_topology, first->type,
                                           first)) {
     ++retval;
   }
   return retval;
 }
 
 static int __kmp_hwloc_count_children_by_depth(hwloc_topology_t t,
-                                               hwloc_obj_t o, unsigned depth,
+                                               hwloc_obj_t o,
+                                               kmp_hwloc_depth_t depth,
                                                hwloc_obj_t *f) {
   if (o->depth == depth) {
     if (*f == NULL)
       *f = o; // output first descendant found
     return 1;
   }
   int sum = 0;
   for (unsigned i = 0; i < o->arity; i++)