How to ignore a broken ".la" file in the base system?

[Matthias Scheler <tron%zhadum.org.uk@localhost>]

        Hello,

Mac OS X Leopard comes with this ".la" file in the base system:

tron@excalibur:~>ls -l /usr/X11/lib/libpng12.la 
-rwxr-xr-x  1 root  wheel  834 10 May 10:41 /usr/X11/lib/libpng12.la
tron@excalibur:~>grep library_names /usr/X11/lib/libpng12.la
library_names='libpng12.0.dylib libpng12.dylib libpng12.0.26.0.dylib'

It is however broken since the latest security update:

tron@excalibur:~>ls -l /usr/X11/lib/libpng12.0.26.0.dylib
ls: /usr/X11/lib/libpng12.0.26.0.dylib: No such file or directory
tron@excalibur:~>ls -l /usr/X11/lib/libpng12.0.24.0.dylib 
lrwxr-xr-x  1 root  wheel  16 30 Mar 23:56 /usr/X11/lib/libpng12.0.24.0.dylib 
-> libpng12.0.dylib

Build failures in "pkgsrc" aren't the only problems caused by that:

http://sarth.thallos.org/2008/07/libpng12dylib-related-compile-failures.html

How can I teach "pkgsrc" to ignore "/usr/X11/lib/libpng12.la"? It finds
it by accident when linking package with options like
"-L/usr/X11R6/lib ... -lpng"

        Kind regards

-- 
Matthias Scheler                                  http://zhadum.org.uk/