Utils: Fix `lengthIs` and `lengthExceeds` for negative args
Utils: Fix `lengthIs` and `lengthExceeds` for negative args

Credits goes to SPJ for finding this.

sdiehl/ghc,ezyang/ghc,sdiehl/ghc,sdiehl/ghc,sgillespie/ghc,snoyberg/ghc,shlevy/ghc,ezyang/ghc,vTurbine/ghc,ezyang/ghc,shlevy/ghc,shlevy/ghc,ezyang/ghc,sgillespie/ghc,olsner/ghc,shlevy/ghc,mettekou/ghc,vTurbine/ghc,mettekou/ghc,vTurbine/ghc,snoyberg/ghc,sgillespie/ghc,mettekou/ghc,shlevy/ghc,snoyberg/ghc,vTurbine/ghc,sdiehl/ghc,mettekou/ghc,snoyberg/ghc,vTurbine/ghc,sgillespie/ghc,olsner/ghc,snoyberg/ghc,olsner/ghc,ezyang/ghc,snoyberg/ghc,vTurbine/ghc,snoyberg/ghc,shlevy/ghc,sgillespie/ghc,ezyang/ghc,mettekou/ghc,sdiehl/ghc,sdiehl/ghc,mettekou/ghc,olsner/ghc,vTurbine/ghc,sgillespie/ghc,olsner/ghc,shlevy/ghc,sgillespie/ghc,sdiehl/ghc,ezyang/ghc,olsner/ghc,olsner/ghc,mettekou/ghc