Tidy up tidying
Tidy up tidying

This is a tiny refactor, replacing an ad-hoc local function
(TidyPgm.loookup_aux_id) with a solid global one (tidyVarOcc).

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