Problem building mozilla for MacOSX

Hi,

I downloaded the Mozilla 1.7.2 source tarball and want to build it. 
However ./configure breaks with the following message:

<snip>

checking for XShmCreateImage in -lXext... yes
checking for X11/extensions/XShm.h... yes
checking for XieFloGeometry in -lXIE... no
checking for X11/extensions/XIElib.h... no
configure: error: Could not compile basic X program.

</snip>

Briefly, my setup is:

MacOSX 10.3.5
DeveloperTools 1.5 (X11SDK installed)
Apple X11 1.0 at X4.3
fink 0.21.2 with
   - orbit 0.5.17-16
   - orbit-dev 0.5.17-16
   - glib 1.2.10-18
   - zip and unzip 2.3-3 and 5.50-14 respectively
SharedMenusCocoa framework is installed

I cannot find a libXIE or XIElib.h anywhere on my system ... it seems 
this is what is causing the break.  Where do I get them?

Thanks,

Fred