Bug 750625 - Fix Coverity (11112) Uninitialized pointer read

https://bugzilla.redhat.com/show_bug.cgi?id=750625

plugins/replication/repl5_replica_config.c (replica_execute_ldif2cl_task)

Bug Description: Using uninitialized "config.dir" when calling
"cl5Open".
config.dir is set in changelog5_extract_config.  If any error
such as fail to read changelog config entry, NULL is set and
following cl5Open fails.

Fix Description: check if config.dir is NULL or not in error logging.

ldap/servers/plugins/replication/repl5_replica_config.c

@@ -1052,7 +1052,7 @@ static int replica_execute_ldif2cl_task (Object *r, char *returntext)
     {
         slapi_log_error(SLAPI_LOG_FATAL, repl_plugin_name, 
             "replica_execute_ldif2cl_task: failed to start changelog at %s\n",
-            config.dir);
+            config.dir?config.dir:"null config dir");
         rc = LDAP_OPERATIONS_ERROR;    
     }
 bail: