This addresses failures like

  In file included from dlls/nsiproxy.sys/udp.c:34:
  In file included from /usr/include/sys/socketvar.h:38:
  In file included from /usr/include/sys/selinfo.h:36:
  /usr/include/sys/event.h:77:2: error: unknown type name 'u_short'

on non-Linux platforms.
Signed-off-by: Gerald Pfeifer <gerald@pfeifer.com>
Signed-off-by: Huw Davies <huw@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>