Instead of size_t use orte_std_cntr_t. Remove all warnings.

This commit was SVN r12280.

orte/mca/pls/rsh/pls_rsh.h

@@ -72,8 +72,8 @@ struct orte_pls_rsh_component_t {
     int agent_argc;
     char* agent_path;
     char* orted;
-    size_t num_children;
-    size_t num_concurrent;
+    orte_std_cntr_t num_children;
+    orte_std_cntr_t num_concurrent;
     opal_mutex_t lock;
     opal_condition_t cond;
 };