(MacOS) only: In the System tab of the user preferences the user has the
ability to select a GPU backend that Blender will use. After changing
the GPU backend setting, the user has to restart Blender before the
setting is used.
It was added to start collecting feedback on the Metal backend without
using the command lines.
By default Blender will select OpenGL as backend. When Metal is selected
(via --gpu-backend metal or via user preferences) OpenGL will be used as
fallback when the platform isn't capable of running Metal.
NOTE: This patch requires a version bump, that isn't included in the patch yet. It will be added just before committing.
NOTE: This patch will only be committed after Metal backend is enabled in master.