Do not reinstall preinstalled packages under AppVeyor.
Do not reinstall preinstalled packages under AppVeyor.

It seems that reinstalling gcc can leave Cygwin in a strange state,
where invocations of gcc fail suddenly. I haven't figure out exactly
why, but this seems to fix it.

ppedrot/coq,Matafou/coq,SkySkimmer/coq,letouzey/coq-wip,gares/coq,ejgallego/coq,coq/coq,coq/coq,letouzey/coq-wip,Matafou/coq,ejgallego/coq,maximedenes/coq,Zimmi48/coq,Zimmi48/coq,SkySkimmer/coq,ppedrot/coq,maximedenes/coq,silene/coq,gares/coq,SkySkimmer/coq,maximedenes/coq,silene/coq,ppedrot/coq,coq/coq,gares/coq,gares/coq,Matafou/coq,ejgallego/coq,JasonGross/coq,Zimmi48/coq,gares/coq,maximedenes/coq,letouzey/coq-wip,silene/coq,JasonGross/coq,ppedrot/coq,letouzey/coq-wip,JasonGross/coq,SkySkimmer/coq,Zimmi48/coq,coq/coq,letouzey/coq-wip,JasonGross/coq,maximedenes/coq,ppedrot/coq,ejgallego/coq