I don't exactly remember the state of using Vc when krita separated from Calligra, but it would probably be best to remove it entirely. Nothing in Calligra is going to use any of this code at any point: it is used to blend layers together in Krita, and everything else in Calligra uses Qt for that.
It would be best to completely remove pigment, except for KoColorSet, but that also means replacing all use of KoColor with QColor. There used to be a compile-time switch for that, in the Nokia days.
(I know that there have been plans for over a decade to use pigment to have color managed images in Words, but pigment probably isn't the right solution for that anyway...)