users_guide: Break up -fprint-* description
users_guide: Break up -fprint-* description

This makes it a bit easier to find the description corresponding to
particular flags.

mettekou/ghc,tjakway/ghcjvm,olsner/ghc,snoyberg/ghc,tjakway/ghcjvm,vTurbine/ghc,vTurbine/ghc,olsner/ghc,ezyang/ghc,mettekou/ghc,mettekou/ghc,snoyberg/ghc,sdiehl/ghc,vikraman/ghc,vikraman/ghc,tjakway/ghcjvm,sgillespie/ghc,snoyberg/ghc,ezyang/ghc,sdiehl/ghc,sdiehl/ghc,olsner/ghc,sdiehl/ghc,shlevy/ghc,tjakway/ghcjvm,olsner/ghc,vTurbine/ghc,mcschroeder/ghc,sdiehl/ghc,mcschroeder/ghc,snoyberg/ghc,sgillespie/ghc,ezyang/ghc,vikraman/ghc,sgillespie/ghc,sdiehl/ghc,vTurbine/ghc,ezyang/ghc,tjakway/ghcjvm,mcschroeder/ghc,ezyang/ghc,shlevy/ghc,sgillespie/ghc,vikraman/ghc,mettekou/ghc,sdiehl/ghc,vikraman/ghc,ezyang/ghc,shlevy/ghc,vikraman/ghc,mettekou/ghc,olsner/ghc,tjakway/ghcjvm,olsner/ghc,snoyberg/ghc,mcschroeder/ghc,sgillespie/ghc,mcschroeder/ghc,vTurbine/ghc,shlevy/ghc,snoyberg/ghc,shlevy/ghc,ezyang/ghc,vikraman/ghc,tjakway/ghcjvm,shlevy/ghc,vTurbine/ghc,mcschroeder/ghc,snoyberg/ghc,olsner/ghc,mettekou/ghc,sgillespie/ghc,vTurbine/ghc,mcschroeder/ghc,shlevy/ghc,mettekou/ghc,sgillespie/ghc