fix get_ib_dev_distance: it doesn't see processes as bound if the job has been launched by srun

diff -r 162c1c0c050a ompi/mca/btl/openib/btl_openib_component.c
--- a/ompi/mca/btl/openib/btl_openib_component.c        Thu Jan 26 21:42:13 2012 +0000
+++ b/ompi/mca/btl/openib/btl_openib_component.c        Fri Jan 27 16:36:29 2012 +0100
@@ -2332,11 +2332,20 @@ static int get_ib_dev_distance(struct ib
 {
     opal_paffinity_base_cpu_set_t cpus;
     opal_carto_base_node_t *device_node;
-    int min_distance = -1, i, num_processors;
+    int min_distance = -1, i;
+    int num_processors = OPAL_PAFFINITY_BITMASK_CPU_MAX;
     const char *device = ibv_get_device_name(dev);
 
-    if(opal_paffinity_base_get_processor_info(&num_processors) != OMPI_SUCCESS) {
-        num_processors = 100; /* Choose something big enough */
+    if (opal_paffinity_base_get_processor_info(&num_processors) != OMPI_SUCCESS
+            || 1 == num_processors) {
+        /*
+         * We get num_processors=1 if we were launched using srun + binding:
+         * in that case we are placed in a cpuset that contains a single cpu
+         * (the one we were bound to)
+         *     ==> the loop after won't be correctly executed
+         */
+        /* Choose something big enough */
+        num_processors = OPAL_PAFFINITY_BITMASK_CPU_MAX;
     }
 
     device_node = opal_carto_base_find_node(host_topo, device);