just a few split out patches from my zoo of local work ...
The patch to simgear-glxproc.diff changes dlopen to not open a specific library.
If it is used with a NULL argument, we just get a handle to the current running
binary including all loaded libraries. This has the advantage that we do not
rely on the name of libGL on the specific platform.
Also a user can link with his own different named libGL or with a static libGL.a
Then the render texture again ...
glxQueryVersion turns out to return the minimum of the client libraries glx
version and the servers glx version. *All* Xorg servers return 1.2 here.
So we never get the glxPBuffer functions which are the only ones working with
ati's drivers ...
Reverted back to checking the required functions and just use them if they are
there. Still prefering the glx standard variants since they work on ati's
drivers ...