Backported from X.org:

 commit fd8bde8bb0f9d796b3464973b53285c0a6d22a31
 Author: Daniel Stone <daniel@fooishbar.org>
 Date:   Mon May 29 11:14:03 2006 +0000

    Remove -xkbmap argument.
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>