[cbv] Fix evaluation of cofixpoints under primitive projections.
[cbv] Fix evaluation of cofixpoints under primitive projections.

Fixes #5286 (last remaining part).

gares/coq,JasonGross/coq,maximedenes/coq,maximedenes/coq,Zimmi48/coq,silene/coq,letouzey/coq-wip,ppedrot/coq,Zimmi48/coq,Zimmi48/coq,letouzey/coq-wip,letouzey/coq-wip,ppedrot/coq,ejgallego/coq,ejgallego/coq,ppedrot/coq,silene/coq,gares/coq,letouzey/coq-wip,coq/coq,JasonGross/coq,JasonGross/coq,gares/coq,coq/coq,letouzey/coq-wip,gares/coq,gares/coq,Matafou/coq,Zimmi48/coq,SkySkimmer/coq,ejgallego/coq,coq/coq,coq/coq,Matafou/coq,Matafou/coq,silene/coq,SkySkimmer/coq,JasonGross/coq,ppedrot/coq,ppedrot/coq,maximedenes/coq,ejgallego/coq,SkySkimmer/coq,SkySkimmer/coq,maximedenes/coq,maximedenes/coq