newbie trouble building Squeak VM on Mac

Hi,

it's my first attempt ever to actually build a Squeak VM, hence the
crosspost to both the beginners' and VM dev lists.

I have checked out the latest VM sources from svn today, run the
configure script (for the unix platform - I have a G4 PowerBook
running Mac OS X 10.4.7), and issued "make Squeak.app".

Eventually, the build stops with an error:

/Users/haupt/squeakvm/squeak-svn/platforms/unix/plugins/B3DAcceleratorPlugin/sqUnixOpenGL.h:26:7:
error: #error *** cannot find gl.h

Huh. Apparently the configure script thought there was OpenGL on the
machine, didn't it? Anyway, where / how can I obtain that file or
exclude OpenGL support?

Thanks in advance,

Michael