Extrude the computation of redexp flags in reduce.
Extrude the computation of redexp flags in reduce.

This was a source of slowdown observed in bedrock2.

coq/coq,coq/coq,ejgallego/coq,JasonGross/coq,silene/coq,SkySkimmer/coq,JasonGross/coq,Zimmi48/coq,JasonGross/coq,SkySkimmer/coq,ejgallego/coq,JasonGross/coq,silene/coq,coq/coq,ejgallego/coq,Zimmi48/coq,Zimmi48/coq,coq/coq,ejgallego/coq,SkySkimmer/coq,SkySkimmer/coq,Zimmi48/coq,silene/coq