...as long as the mAB tag doesn't have A curves and a CLUT.
With this, we can convert images that use AToB* tags to the profile
connection space (and then from there to, say, sRGB), if the AToB* tag
uses the mAB format.
We can't yet do this if the mAB tag has A curves or a CLUT.
We can't convert back from PCS to this space yet.
We don't yet handle AToB* tags that use mft1 or mft2 instead of mAB.
c25538b2e3