Fix minor memory leaks

This commit was SVN r13946.

opal/runtime/opal_params.c

@@ -71,6 +71,7 @@ int opal_register_params(void)
         mca_base_param_reg_string_name("opal", "signal", 
                                        "If a signal is received, display the stack trace frame",
                                        false, false, string, NULL);
+        free(string);
     }
 
 #if OMPI_ENABLE_DEBUG

opal/util/stacktrace.c

@@ -416,6 +416,7 @@ int opal_util_register_stackhandlers (void)
         return OPAL_ERR_IN_ERRNO;
       }
     }
+    free(string_value);
 #endif /* OMPI_WANT_PRETTY_PRINT_STACKTRACE && ! defined(__WINDOWS__) */
 
     return OPAL_SUCCESS;

orte/util/pre_condition_transports.c

@@ -154,6 +154,7 @@ int orte_pre_condition_transports(orte_app_context_t **app_context, size_t num_c
     }
 
     free(cs_env);
+    free(string_key);
 
     return ORTE_SUCCESS;
 }