Remove warning-suppression flags for Cabal
Remove warning-suppression flags for Cabal

Cabal is currently warning free. So let's drop the `-w`-flags.

/cc @dcoutts

mettekou/ghc,snoyberg/ghc,vikraman/ghc,ezyang/ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,vTurbine/ghc,mcschroeder/ghc,oldmanmike/ghc,sdiehl/ghc,nushio3/ghc,tjakway/ghcjvm,mcschroeder/ghc,sdiehl/ghc,vikraman/ghc,ezyang/ghc,vTurbine/ghc,sdiehl/ghc,GaloisInc/halvm-ghc,gridaphobe/ghc,oldmanmike/ghc,mettekou/ghc,gridaphobe/ghc,mcschroeder/ghc,ezyang/ghc,shlevy/ghc,tjakway/ghcjvm,nushio3/ghc,olsner/ghc,gridaphobe/ghc,gridaphobe/ghc,sdiehl/ghc,oldmanmike/ghc,oldmanmike/ghc,sgillespie/ghc,oldmanmike/ghc,oldmanmike/ghc,snoyberg/ghc,olsner/ghc,snoyberg/ghc,vTurbine/ghc,olsner/ghc,shlevy/ghc,GaloisInc/halvm-ghc,olsner/ghc,gridaphobe/ghc,mcschroeder/ghc,snoyberg/ghc,mettekou/ghc,mettekou/ghc,nushio3/ghc,ezyang/ghc,sgillespie/ghc,GaloisInc/halvm-ghc,vikraman/ghc,mettekou/ghc,nushio3/ghc,sdiehl/ghc,vikraman/ghc,tjakway/ghcjvm,mcschroeder/ghc,vTurbine/ghc,mettekou/ghc,ezyang/ghc,mcschroeder/ghc,snoyberg/ghc,nushio3/ghc,shlevy/ghc,sgillespie/ghc,mettekou/ghc,GaloisInc/halvm-ghc,olsner/ghc,snoyberg/ghc,vTurbine/ghc,shlevy/ghc,shlevy/ghc,nushio3/ghc,olsner/ghc,shlevy/ghc,ezyang/ghc,sgillespie/ghc,tjakway/ghcjvm,gridaphobe/ghc,tjakway/ghcjvm,mcschroeder/ghc,oldmanmike/ghc,vTurbine/ghc,snoyberg/ghc,vikraman/ghc,shlevy/ghc,sgillespie/ghc,olsner/ghc,vikraman/ghc,tjakway/ghcjvm,vTurbine/ghc,sdiehl/ghc,sdiehl/ghc,ezyang/ghc,gridaphobe/ghc,sgillespie/ghc,nushio3/ghc,sgillespie/ghc,vikraman/ghc,tjakway/ghcjvm,GaloisInc/halvm-ghc