avoid spurious error when looking up UIDs not in winbindd's idmap range

i'm not 100% sure that's what is causing the problem, but it seems fairly
innocuous to suppress this error only for getpwuid lookups

https://forums.proftpd.org/smf/index.php/topic,5630.0/all.html

Author: jwm

mod_winbind.c

@@ -313,7 +313,7 @@ handle_winbind_uid_name(cmd_rec *cmd)
 
   ret = wbcGetpwuid(*((uid_t *) cmd->argv[0]), &pw);
   if (!WBC_ERROR_IS_OK(ret)) {
-    if (ret != WBC_ERR_UNKNOWN_USER) {
+    if ((ret != WBC_ERR_UNKNOWN_USER) && (ret != WBC_ERR_DOMAIN_NOT_FOUND)) {
       pr_log_pri(PR_LOG_ERR,
         MOD_WINBIND_VERSION ": unable to look up user with UID %u: %s",
         *((unsigned *) cmd->argv[0]), wbcErrorString(ret));