Fix shelving order in typeclasses eauto.
Fix shelving order in typeclasses eauto.

Before this fix, unshelve typeclasses eauto would produce sub-goals
in the reverse order compared to when they were first shelved.

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