Silence stupid compiler warning - and a certain someone who keeps reminding me of it... :-)

This commit was SVN r19031.

orte/mca/grpcomm/base/grpcomm_base_modex.c

@@ -292,7 +292,7 @@ int orte_grpcomm_base_set_proc_attr(const char *attr_name,
     OPAL_OUTPUT_VERBOSE((5, orte_grpcomm_base_output,
                          "%s grpcomm:set_proc_attr: setting attribute %s data size %lu",
                          ORTE_NAME_PRINT(ORTE_PROC_MY_NAME),
-                         attr_name, size));
+                         attr_name, (unsigned long)size));
 
     /* Pack the attribute name information into the local buffer */
     if (ORTE_SUCCESS != (rc = opal_dss.pack(modex_buffer, &attr_name, 1, OPAL_STRING))) {