Add a [map_ext_in] lemma to List.v.
Add a [map_ext_in] lemma to List.v.

Slightly broader version of the existing [map_ext]: two [map] expressions
are equal if their respective functions agree on all arguments that are
in the list being mapped.

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