astro/celestia-gtk-1.4.2 does not build (link error)

[Patrick Lamaizière]

Hello,

I can't update astro/celestia-gtk-1.4.2 because a link error with 
libgtk-x11-2.0.la :

libtool: link: cannot find the library `/usr/X11R6/lib/libgtk-x11-2.0.la' or 
unhandled argument `/usr/X11R6/lib/libgtk-x11-2.0.la'
gmake[4]: *** [celestia] Erreur 1

libgtk-x11-2.0.la is in /usr/local/lib, why libtool thinks it is 
in /usr/X11R6/lib ? 

Thanks, regards.