I have been fighting the same problem with getting SUMA to compile under leopard. The problem is that Apple saw fit to omit the open GL widget library (lilbGLw.a) from 10.5 (see [lists.apple.com]) .

I was able to fix the problem by first downloading the Mesa library implementation of openGL from [sourceforge.net]. The GLw libraries will not build under darwin for this release, but if you add "glw" to the list of sources to build it will build the correct object module. You can then cd to the src/glw subdirectory and build the static library with the command:
../../bin/mklib -o GLw -linker 'gcc' -ldflags '' -static -L/usr/X11/lib -lX11 -lXt -lGL GLwDrawA.o

libGLw.a is only a few kbytes long. I will email to anyone who needs it.

AFNI will then build. A quick check shows that 3dSkullStrip works properly and so does the viewer. I am amazed that his actually worked.

The library is only 4k long, so I attached it to this email.

If there is interest, I could package up my binaries and put them on the web.

John