In Issue #5475 we decided to remove OpenGL but keep OpenGLCompute; AFAICT, we don't do any testing at all on the OpenGLCompute backend. The only thing in our code that appears to explicitly test it is apps/openglcompute, which is Android-specific (and hasn't been built in ~years). If we intend to keep this backend, we need to add some level of testing for it on the buildbots.