Issue 49188 - retrocl can crash server at shutdown

Description:  We do not calloc enough elements when processing nsslapd-attribute
              from the retrocl plugin configuration.  This causes invalid memory
              to be freed at shutdown(via slapi_ch_array_free).

https://pagure.io/389-ds-base/issue/49188

Reviewed by: mreynolds(one line commit rule)

ldap/servers/plugins/retrocl/retrocl.c

@@ -470,8 +470,8 @@ static int retrocl_start (Slapi_PBlock *pb)
 
         retrocl_nattributes = n;
 
-        retrocl_attributes = (char **)slapi_ch_calloc(n, sizeof(char *));
-        retrocl_aliases = (char **)slapi_ch_calloc(n, sizeof(char *));
+        retrocl_attributes = (char **)slapi_ch_calloc(n + 1, sizeof(char *));
+        retrocl_aliases = (char **)slapi_ch_calloc(n + 1, sizeof(char *));
 
         slapi_log_err(SLAPI_LOG_PLUGIN, RETROCL_PLUGIN_NAME, "retrocl_start - Attributes:\n");