It's broken and it's not needed anymore, since we require OpenGL 4.3.
Fix#142620
Note: Debug callbacks still won't work for compilation threads,
but that's relatively harmless and should cause no issues for the user.
This will be fixed in 5.0 with #142715.
(4.5 backport candidate)
Pull Request: https://projects.blender.org/blender/blender/pulls/142716
b43616513a