There is no such thing that is widely known as the "Linux ABI" _and_ that mandates things like this.
Do you refer to http://oss.sgi.com/projects/ogl-sample/ABI/ ?
Yes.
If we're nitpicking, this has nothing to do with an ABI, but with an API.
Well, the documentation is called an ABI so I take their naming conventions even if in the case of header file definitions I agree with you.
If we are not nitpicking, this problem still exists with Mesa-5.0.1, so it would be nice to address it (as Raphaël once suggested).
Well, feel free to do so, this is a can of worm that I do not particularly like to open (and it works for me (tm)).
But I will post a mail on the Mesa-devel mailing list about the glXGetProcAddressARB issue, we will see what I get for an answer :-)
Lionel