Revert "Specially crafted EConstr.kind to be more efficient."
Revert "Specially crafted EConstr.kind to be more efficient."

This reverts commit b5f07be9fdcd41fdaf73503e5214e766bf6a303b. The performance
difference was not conclusive enough to pay for the code ugliness.

coq/coq,maximedenes/coq,SkySkimmer/coq,william-lawvere/coq,william-lawvere/coq,letouzey/coq-wip,Zimmi48/coq,SkySkimmer/coq,coq/coq,ppedrot/coq,gares/coq,letouzey/coq-wip,Matafou/coq,JasonGross/coq,maximedenes/coq,letouzey/coq-wip,silene/coq,Lionel-Rieg/coq,ppedrot/coq,ejgallego/coq,Matafou/coq,JasonGross/coq,maximedenes/coq,Zimmi48/coq,ppedrot/coq,amintimany/coq,SkySkimmer/coq,letouzey/coq-wip,silene/coq,ppedrot/coq,ejgallego/coq,JasonGross/coq,Lionel-Rieg/coq,Zimmi48/coq,amintimany/coq,ejgallego/coq,ejgallego/coq,coq/coq,amintimany/coq,Lionel-Rieg/coq,maximedenes/coq,letouzey/coq-wip,gares/coq,Matafou/coq,SkySkimmer/coq,maximedenes/coq,JasonGross/coq,silene/coq,william-lawvere/coq,ppedrot/coq,Zimmi48/coq,gares/coq,coq/coq,gares/coq,gares/coq