Problems getting X11 to work

Hello

I have downloaded and tried to build the September 2006 version of Hugs 
on my Intel Mac, Mac OS X 10.4. The build completes and I can run Hugs 
just fine, but I can't get X11 to work.

Here is a small part of the make log:

Reading parameters from 
/Users/Emil/Desktop/Downloads/hugs98-plus-Sep2006/packages/X11/X11.buildinfo
Preprocessing 

library X11-1.2...
../../libraries/tools/hsc2hs -D__HUGS__ -Iinclude --lflag=-lX11 -o 
Graphics/X11/Types.hs Graphics/X11/Types.hsc
/usr/bin/ld: can't locate file for: -lX11
collect2: ld returned 1 exit status
linking Graphics/X11/Types_hsc_make.o failed
command was: /usr/bin/gcc -lX11 Graphics/X11/Types_hsc_make.o -o 
Graphics/X11/Types_hsc_make
../../packages/Cabal/examples/hapax.hs: got error code while 
preprocessing: Graphics.X11.Types
Skipping X11 package

So apparently it can't locate file for -lX11. This is wierd as I have 
installed both XCode 2.4 and X11. On my harddisk there is a directory 
/usr/X11R6 with lots of stuff in it.

I suspect that there is some kind of argument that can be supplied to 
the comfigure or make commands, but I can't guess it. Perhaps some of 
you know the answer.

The complete log files of configure and make can be found at 
http://emilhedevang.googlepages.com/haskell/.

From
Emil Hedevang