The OpenGL extension `GL_ARB_shader_viewport_layer_array` wasn't turned
off when starting blender with `--debug-gpu-force-workarounds`. Although
all known supported platforms support this extension and we haven't seen
any failures with it, it was mentioned to be phased out as we consider
it to be a core extension, which it isn't.
This PR will enable the workaround for this extension and remove the
extension from the phase out list.
Pull Request: https://projects.blender.org/blender/blender/pulls/113572
76a1824c52