[gtkada] OpenGl in testgtk under w2k

[Arnaud Charlet]

gtkada and testgtk are by default configured/built without opengl
support. The reason is first because 'configure' by default under Windows
does not detect opengl, and also because testgtk does not work properly
with opengl (never did), and that we have no specific opengl skills/interest
to fix this.

You need to start from the source package where all the preprocessed
files are there for opengl support, unlike the windows package which is
a semi-binary package.

Arno