'cabal sdist': don't create a default Setup.hs in current dir.
'cabal sdist': don't create a default Setup.hs in current dir.

See discussion in #1353.

typelead/epm,christiaanb/cabal,beni55/cabal,rimmington/cabal,martinvlk/cabal,themoritz/cabal,thomie/cabal,mightybyte/cabal,fugyk/cabal,gbaz/cabal,mmakowski/cabal,rimmington/cabal,christiaanb/cabal,eric-stanley/cabal,valderman/cabal,Heather/cabal,ghc-android/cabal,plow-technologies/cabal,kosmikus/cabal,garetxe/cabal,trskop/cabal,plow-technologies/cabal,seereason/cabal,sopvop/cabal,enolan/cabal,themoritz/cabal,anton-dessiatov/cabal,lukexi/cabal,randen/cabal,ian-ross/cabal,gridaphobe/cabal,beni55/cabal,lukexi/cabal,trskop/cabal,sopvop/cabal,Peaker/cabal,seereason/cabal,Helkafen/cabal,bennofs/cabal,triplepointfive/cabal,randen/cabal,fugyk/cabal,anton-dessiatov/cabal,enolan/cabal,kosmikus/cabal,plumlife/cabal,corngood/cabal,kolmodin/cabal,garetxe/cabal,themoritz/cabal,headprogrammingczar/cabal,kolmodin/cabal,x-y-z/cabal,mydaum/cabal,Heather/cabal,thomie/cabal,sopvop/cabal,martinvlk/cabal,thoughtpolice/cabal,thoughtpolice/cabal,x-y-z/cabal,ian-ross/cabal,eric-stanley/cabal,Helkafen/cabal,edsko/cabal,triplepointfive/cabal,headprogrammingczar/cabal,fpco/cabal,gridaphobe/cabal,corngood/cabal,Peaker/cabal,mmakowski/cabal,typelead/epm,valderman/cabal,plumlife/cabal,bennofs/cabal,mydaum/cabal,mightybyte/cabal,edsko/cabal,fpco/cabal,ghc-android/cabal,gbaz/cabal