They're completely orthogonal concepts, merged in the past due to
convenience and ease of implementing it in the old #ifdef hell renderer.
Especially after the CMS stuff was generalized by 634b4a, this was a
trivial change to implement and also means color management will be much
higher quality when enabled with vo=opengl (which had quantization
issues in the past due to the 8 bit FBO format and upscaling), since it
can be done in a single pass now.