Created by: kbrenneman
This series adds a dispatch stub for glXCreateContextAttribsARB that can work with the new GLX_EXT_no_config_context extension.
For reference, this is the pull request for the extension spec: https://github.com/KhronosGroup/OpenGL-Registry/pull/102
Strictly speaking, it isn't necessary to put this in libglvnd, since a vendor can still provide a dispatch stub on its own. And still should, to stay compatible with existing libglvnd versions.
However, if you have multiple vendor libraries loaded, then you could run into problems if the dispatch stub happened to come from a vendor that doesn't support GLX_EXT_no_config_context. Putting a dispatch stub into libglvnd avoids that.
The first commit adds the dispatch stub, and the rest of series are updates to the unit tests to exercise both paths through glXCreateContextAttribsARB and to improve test coverage for context creation in general.