Spotted in and backported from X.org:

 commit 021fc5cb2cb4a7972b4a6fcb570c1da92787d68d
 Author: Adam Jackson <ajax@benzedrine.nwnk.net>
 Date:   Sun Mar 18 16:31:19 2007 -0400

    Static markup and dead code cull over xkb/.

    The former <X11/extensions/XKBsrv.h> has been pulled into the server now as
    include/xkbsrv.h, and the world updated to look for it in the new place,
    since it made no sense to define server API in an extension header.  Any
    further work along this line will need to do similar things with XKBgeom.h
    and friends.
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>