xrdb preprocessing

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

I just upgraded a laptop to the -current/i386 xorg, and for some reason
preprocessing doesn't seem to happen when loading xrdb resources any more.

(xrdb -symbols lists all the relevant variables, but the #ifdefs in
/etc/X11/xdm/Xresources behave as comments so there are warnings about
e.g. xlogin*greetFont being defined twice)

  http://bugs.archlinux.org/task/16957?opened=3611&status[0]=

looks relevant, but I haven't taken it further...

Cheers,

Patrick