Per Brice, silence warning on old Linux kernels

Refs trac:3744

This commit was SVN r29179.

The following Trac tickets were found above:
  Ticket 3744 --> https://svn.open-mpi.org/trac/ompi/ticket/3744

opal/mca/hwloc/hwloc172/hwloc/src/topology-linux.c

@@ -272,6 +272,7 @@ hwloc_opendir(const char *p, int d __hwloc_attribute_unused)
 }
 
 
+#if defined(HWLOC_HAVE_CPU_SET_S) && !defined(HWLOC_HAVE_OLD_SCHED_SETAFFINITY)
 static int
 hwloc_linux_parse_cpuset_file(FILE *file, hwloc_bitmap_t set)
 {
@@ -312,7 +313,7 @@ hwloc_linux_parse_cpuset_file(FILE *file, hwloc_bitmap_t set)
 
   return 0;
 }
-
+#endif
 
 /*****************************
  ******* CpuBind Hooks *******