use pool instead of ngx_conf_t

src/mail/ngx_mail_core_module.c

diff --git a/src/mail/ngx_mail_core_module.c b/src/mail/ngx_mail_core_module.c
index 9652330..4f13703 100644
--- a/src/mail/ngx_mail_core_module.c
+++ b/src/mail/ngx_mail_core_module.c
@@ -285,7 +285,7 @@
     u.url = value[1];
     u.listen = 1;
 
-    if (ngx_parse_url(cf, &u) != NGX_OK) {
+    if (ngx_parse_url(cf->pool, &u) != NGX_OK) {
         if (u.err) {
             ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                "%s in \"%V\" of the \"listen\" directive",