Fix convertibility of primitive projections for native_compute.
Fix convertibility of primitive projections for native_compute.

Stuck primitive projections were never convertible.

ppedrot/coq,gares/coq,jpdeplaix/coq,ppedrot/coq,SkySkimmer/coq,maximedenes/coq,ppedrot/coq,ejgallego/coq,TOSPIO/coq,barras/coq,amintimany/coq,8l/coq,JasonGross/coq,amintimany/coq,Lionel-Rieg/coq,ejgallego/coq,gares/coq,SkySkimmer/coq,SkySkimmer/coq,JasonGross/coq,Zimmi48/coq,SkySkimmer/coq,jpdeplaix/coq,herbelin/github-coq,TheTypoMaster/coq,mattam82/coq,Ptival/coq,letouzey/coq-wip,william-lawvere/coq,TheTypoMaster/coq,coq/coq,TOSPIO/coq,letouzey/coq-wip,Lionel-Rieg/coq,coq/coq,herbelin/github-coq,maximedenes/coq,william-lawvere/coq,ejgallego/coq,letouzey/coq-wip,gares/coq,jpdeplaix/coq,JasonGross/coq,TOSPIO/coq,Ptival/coq,mlasson/coq,barras/coq,william-lawvere/coq,Matafou/coq,mattam82/coq,silene/coq,maximedenes/coq,maximedenes/coq,Lionel-Rieg/coq,Matafou/coq,Zimmi48/coq,8l/coq,mlasson/coq,gares/coq,Zimmi48/coq,silene/coq,Ptival/coq,TheTypoMaster/coq,8l/coq,coq/coq,mlasson/coq,letouzey/coq-wip,coq/coq,JasonGross/coq,letouzey/coq-wip,Matafou/coq,barras/coq,silene/coq,ppedrot/coq,mattam82/coq,amintimany/coq,herbelin/github-coq,Zimmi48/coq,maximedenes/coq,ejgallego/coq,ppedrot/coq,gares/coq