[GtkGLExt] Autoconf macros for detecting OpenGL

[Braden McDaniel <braden endoframe com>]

I've recently updated my Autoconf macros for detecting OpenGL libraries
to work on Mac OS X 10.5:

  <http://code.google.com/p/autoconf-gl-macros/>

I mention this here because I found (in the copy of GtkGLExt that I
maintain in my source tree) that Mac OS X 10.5 also posed a challenge
for the logic in GtkGLExt's configure script. Indeed, the challenge was
such that I found it most convenient simply to use AX_CHECK_GLU there as
well. As it happens, a call to AX_CHECK_GLU can replace quite a bit of
code in GtkGLExt's configure.in.

-- 
Braden McDaniel                           e-mail: <braden endoframe com>
<http://endoframe.com>                    Jabber: <braden jabber org>